





1; *K^ rf€^^!:J^^ € 








m^ 









B 










The Barber Asphalt Paving Co. 



IS THE 



Oldes 



It has, up to Jai 

seven Cit 

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presi-:nti-:i) by 



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ents in Twenty- 
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; extent : 

sq. yds. 



LOAL Tak AiNJJ VULCANITE, 04,^^19 

Macadam. - - - 415,686 
Total. 



A. L. Barber, President. 
F. V. Greene, 



1,417,514 

D. O. WiCKHAM, Treasurer. 



E. B. Warren 



J 



Vice-Presidents. 



J. C. Rock, Secretary, 



GENERAL OFFICES I 



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GENERAL AGENTS, 



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P NGINEERING N EWS 

AND 

AMERICAN RAILWAY JOURNAL. 

PUBLISHED WEEKLY BY 

Encineerinc News Publishing Co., 

Tribune Building, New York. 



Sixty Pxges. 
Subscription Price- If^ ''^" Annum. 

SUBSCRIPTION PRICE. -^^2 FOR FoUR MONTHS. 



ENGINEERING NEWS contains each 
week twenty- four pages of valuable read- 
ing matter, covering the entire field of engi- 
neering science in both this and foreign coun- 
tries. Railways, highways, water-works, manu- 
facturing and technical, contracting and 
mechanical and electrical industries are fully 
reported, and detailed working drawings and 
full descriptions are given of all the more 
important and noteworthy structures and 
enterprises. Record is kept of the proceedings 
of all the engineering and technical societies 
and clubs, and the latest technical books and 
magazines are fully reviewed and discussed. 
The correspondence columns contain com- 
munications from engineers, contractors and 
others regarding matters of current interest. 
These are only a few of the many features of 
interest and value. 

On all technical questions relating to railway 
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authority. 



THE 



SCIENCE OF ROAD MAKING. 



CLEMENS HERSCHEL, M. Am. Soc. C. E. 



CONSTRUCTION - MAINTENANCE 
OF ROADS. 



EDWARD P. NORTH, M. Am. Soc. C. E. 



NEW YORK: 
ENGINEERING NEWS PUBLISHING COMPANY, 

1890. 



TC 



4S" 






PREFACE 



The science of roadmaking was revised by Mr. Clemens Herschel 
in 1877, and the paper of Mr. Edward P. North was presented to the 
American Society of Civil Engineers in 1879. To the one was awarded 
the First Prize of the State Board of Agriculture of Massachusetts, and to 
the other the Norman Gold Medal of the American Society of Civil Engi- 
neers. Though considerable advance in processes and machines has 
been made since these dates, these two papers still contain more con- 
densed and valuable information on- a subject now attracting wide-spread 
attention than any similar publication of which we have knowledge. 
Literature on the actual detail of road-making is scarce and fragmentary ; 
and it is with the hope that these two otherwise practically inaccessible 
papers may prove profitable reading to eingineers and others interested in 
road-making that they are now reprinted. 

Gfft 
Mrs.Galllard Hunt 
April 28, 1933 



. i'"^ 






S' 









TABLE OF CONTENTS. 



PART I. 



Introduction. 



Laying Out a Road 6 

Considerations which Determine Best Location 6 

Roman vs. Modern Road Builders 6 

Minimum Radii in Mountainous Districts & 

Concerning Grades, Telford's Rule 7 

Experimental Conclusions 7 

Nomenclature of Roads 7 

Effects of Various Grades on Amount a Horse Can Pull 8 

Width of Roads 9 

Actual Field Work of Laying out the Road 10 

Making the Road Bed 10 

Earthworks, Data for Cost of 11 

Transporting Earth : Shovels and Wheelbarrows 11 

Loosening the Earth (Table) 12 

Portable Railroad and Hand Cars 13 

One-Horse Carts 14 

Shrinkage of Different Soils 14 

Drains and Culverts 15 

Bridges 17 

Making the Road Surface 17 

Foot Paths 17 

Riding Paths 18 

A Good Road Surface 18 

Value of Old Engineering Treatises on Roads 19 

Experience of Older Countries 19 

Chinese Roads 19 

Macadam's Invention 19 

Foundation, or Telford, Roads 20 

Roadbuilding in Baden, Germany 20 

Rules in Prussia for Inclinations , 21 

Macadam Top 21 

Material for Road Covering 22 

Crushing Machinery 23 

Spreading the Material 27 

Practice in Bohemia 27 

Road Rollers 27 

Literature of Steam Road Rollers 28 

Description of Best Horse Road Roller 29 

Estimating Cost of Macadam Road 31 

Gravel Top. Central Park Roads 33 

Comparative Cost of Good and Bad Roads 35 



TABLE OF CONTENTS. 



Keeping Roads in Repair 35 

Value of Constant Repairs 37 

Value of Annual Repairs 37 

Tresaguet's Method in Baden 37 

Comparative Tables of Cost 38 

How to Repair Roads on the Continuous System 39 

Repairs of Macadamized and Much Frequented Streets in Cities 41 

Pavements and Trackways 42 

Stone Pavements 42 

Wooden Pavements 43 

Cast Iron Pavements 44 

Asphalte Pavements 44 

Trackways and Plank Roads 44 

On the Resistance to Motion in the Force Required to Move 

Vehicles on Different Kinds of Roads 45-49 

PART II. 
Best Method of Superintending the Constructing and Repairing 

OF Public Roads 50-60 

APPENDIX. 
An Act for the More Perfect Construction and Maintenance of 
the Common Roads on Highways throughout Massachu- 
setts 61-64 

The Construction and Maintenance op Roads ; 

Earth Roads 65-67 

Macadam 67-82 

Stone Pavements 82-83 

Wood Pavements 83-88 

Asphalte and Bitumen 88 

Compressed Asphalte 90 ' 

Asphaltic Mastic 95 

Bitumen Mastic 97 

Tar Mastic 99 

Appendices 100 

No. 1. Extract from Birmingham (England) Specification 100 

No. 2. Extract from Specification for Telford, Macadam and Trap 

Block Gutters on Fifth avenue, N. Y 100 

No. 3. The Gellerat Roller. \ 103 

The Lindelof Roller 104 

The Aveling & Porter Roller 104 

The Ross Roller 106 

No. 4. A Part of the Contract for the Construction and Maintenance 

of the Streets and Sidewalks of the City of Jassy 107 

No. 5. Abstract of Specifications and Schedule of Prices for the Con- 
struction and Maintenance of Footpaths and Sidewalks in Asphaltic 
Mastic, and the Places and Roadways in Compressed Asphalte be- 
longing to the Municipal Service of Paris, from January 1, 1878, to 

December 31, 1882, Paul Crochet, Contractor 112-117 

Discussion on the Construction and Maintenance of Roads 119 

N[ote on the Nomenclature of Bitumen 143 



THE SCIENCE OF EOAD MAKING. 



INTRODUCTION. 



This treatise was written in answer to the printed circular of a 

Committee of the Board of Agriculture, calling for "treatises 
upon the science of road making, and the best methods of superin- 
tending the construction and repair of public roads in this Com- 
monwealth." 

This circular was issued about the middle of December, and as 
the time for writing and sending in the called-for essays was limi- 
ted to January 28, the writer has thought it best, no specific char- 
acter being prescribed for the treatises, to attempt to write one 
suitable to be so called from the stand-point of the fublic^ rather 
than from that of the civil engineer, and, giving results rather than 
the methods of arriving at them, to be as concise as possible. 



The Science of Road Making. 

Starting, then, with the first of the two subjects mentioned in 
the circular, — the science of road making, we can divide this into 
three periods: i. Laying out a road ; 2. making the road-bed, 
which includes all earthworks, cutting and filling, culverts, drains, 
bridges, even tunnels, etc.; and 3. the making of the road surface; 

♦A First Prize Treatise awarded to the Author by the State Board of AgricuL 
ture, of Massachusetts. 



THE SCIENCE OF ROAD MAKING. 



to which, not improperly might be added, 4. keeping the road in 
repair. 

Laying out a Road. 

The considerations which determine the best location of a road, 
are those arising from the nature of the travel it is proposed to 
accommodate; that is, from the admissible grades, radii of curves, 
etc. Given two points it is desired to connect, with no intermedi- 
ate point where the road is to touch, that route is the best which 
will cost least to build and maintain, the grades and curves being 
kept within bounds ; and to find this location constitutes the whole 
problem of the engineer. | 

In older countries, where trade and manufactures are more 
settled and unchanging than in the United States, the probable 
future travel upon a road about to be laid out and built, forms a 
material element in the data that govern its alignment and grades. 
A very able and clever article upon this subject may be found in the 
Journal of the Society of Civil Engineers and Architects at Han- 
over," for the year 1869, and also in pamphlet form. It is in the 
German language, written by Launhardt, Superintendent of High- 
ways (and a civil engineer) in the Hanoverian provinces. 

The Romans built all of their roads in perfectly straight lines, 
up hill and down, at a very great expense, as being absolutely the 
shortest distance between two points. At a later period in history, 
it was argued that a road must be winding to be agreeable, and 
many were so built only for this reason. The modern road- 
builder or engineer in general, ignores any such considerations, and 
has for his aim only to achieve the most, at the least present and 
future expense. ^ 

As regards curves in roads in a hilly or mountainous district, 
we have then the rules never to make a smaller radius than 30 feet, 
and that only in extraordinary cases. On roads where long log- 
ging or other wagons may be expected, the smallest radius ought 
to be 50 or 60 feet ; and, in general, 40-45 feet is none too much. 

A rule sometimes followed in constructing mountain roads, is, 
where the inclination is i or 2 in a hundred, f heavy teams require 

f In describing grades, the first figure gives the vertical height which is ascended 
in a horizontal distance given by the second figure. Both figures must of course 
be taken to refer to the same unit of length, thus : 100 feet in 120 feet, 100 inches 
in 120 inches, or 100 miles in 120 miles, all express the same inclination to a level 
plane, and are more general in their application than the ways of expressing grades 
in so many inches to the foot, or feet in one mile, etc., etc. 



THE SCIENCE OF ROAD MAKING, 




40/ and light ones 30/ radius; with a grade of 2 or 3 in a hundred, 
heavy teams require 65/ and light ones 50/ ra- 
dius. Where a reverse curve [shaped like the 
letter S] occurs, there should be a straight piece 
connecting the two curves [Fig, 
I.] On the contrary, where the 
two curves to be connected are 
concave in the same direction, the 
^®* *• connecting link should be curved 

also, and not straight, [Fig. 2.] On the length 
of the curves the grade should be made easier 
than on the parts of the road immediately ad- 
joining. 

As regards grades, to start with mountain paths, we find pedes- 
trians able to walk up an inclination of 100 in 120; mules, ponies, 
■etc., 100 in 173. For roads, Telford's rule was, that for horses 
attached to ordinary vehicles to trot up a hill rising 3 in 100, was 
equal to walking up one of a 5 in a 100 grade. 
Experiments have shown that — 

1. On a road falling 2 in a hundred, vehicles would run down 
of themselves. 

2. On the same kind of road, but having an inclination of 4 
in a hundred, light vehicles had to be held back lightly, loaded ones 
with considerable force. 

3. On a road having a fall of 51^^ in a hundred, light vehicles 
had to be held back with considerable force, or if a brake was 
applied they had to be pulled, whereas heavy or loaded vehicles 
had to be braked to keep the horses from being speedily exhausted. 

On inclinations steeper than 5 in a hundred, the rainwater run- 
ning down the road is apt to do some damage to the road surface. 

The regulations of different countries having a long experience 
in road building, such as France, Prussia, Baden, etc., vary some- 
what, but the following is the general result: 

In treating of roads, it often renders the subject much clearer, 
to divide them into three classes : first, second, and third class roads, 
or, as we might also say, state, county and town roads. Accepting 
this nomenclature, we have this: for first-class or state roads, the 



8 THE SCIENCE OF ROAD MAKING. 

greatest inclination should not exceed 3—5 in a hundred ; second-class 
or county roads, 5-7 in a hundred; third-class or town roads, 7-10 
in a hundred. A road rising 10 in a hundred is not supposed ever 
to have any heavy teams upon it. In ascending a hill it is wrell and 
proper to decrease the grade as the top is reached, and in the same 
measure as the horses get tired. Thus, if a first-class road starts 
up hill with a grade of 4^ per hundred, it should gradually dimin- 
ish to 4 and 31^ in a hundred, and end near the top with a grade of 
3 in a hundred. 

Launhardt, the superintendent of highways, and engineer, men- 
tioned in the previous note, has a valuable article on the subject 
of the best grades for highways, in the Engineering journal there 
mentioned, for the year 1867; re-printed also in pamphlet form- 
He shows in this article that, according to the received formula 
that expresses the relations between the tractive force, the velocity 
in feet per second, and the daily working hours that go to pro^ 
duce the maximum amount of work that can be got out of a 
draught-horse, a uniform grade between any two points, except 
perhaps in curves, and, if desired, for resting places, is the grade that 
tends to enable the horse or other draught animal to produce the 
most work per diem. 

If a grade of 4 or 5 in a hundred must needs be kept up for 
some distance, then it is well to have resting places 40 or 50 feet 
long, having a grade of only \% ox two in a hundred, in the 
line of the road at proper intervals. An expedient adopted by TeU 
ford, the eminent English engineer, in order to avoid making a. 
piece of road a mile long, on a less grade than 5 in a hundred, on 
account of the increased cost this would have occasioned, and yet 
not have this part of the road too much more tiresome for the 
horses than the rest, was to make the road-surface on this mile of a 
much better quality than on the remainder; the additional cost 
required for the improved road-bed amounting to only about one- 
half of what it would have cost to reduce the grade to say 4 in a 
hundred, as will be again referred to under the head of trackways.. 
In sharp curves the grade should be only i or 2 in a hundred or 
level. 

The following table gives the effects of various grades on the 
amount a horse can pull, and is based on calling the load a horse 
will pull on a level, one : — 



THE SCIENCE OF ROAD MAKING. 



Then, on 


a grade 


of 


1 : 100, a 


horse 


can pull 


M 


«( 




i: 50, 


" 




«« 


«( 




I: 44. 


« 




«< 


« 




I: 40, 


ti 




«< 


•» 




I: 30, 


*• 




« 


4< 




I: 26, 


'* 




1* 


" 




i: 24, 


•• 




M 


«4 




I: 20, 


" 




t< 


14 




I: 10, 


•• 





0.90 

0.81 

0.75 

0.72 

" 0.64 

0.54 

0.50 

0.40' 

0.25 

To determine whether it is most advisable to go over or around 
a hill, all other considerations being equal, w^e have this rule : Call 
the difference between the distance around on a level and that over 
the hill , t/, the distance around being taken as the greatest, and call 
h^ the height of the hill. 

Then in case of a first class road, we go round when d is less 
than \6 h. 

And in case of a second class road, we go around when d is less- 
than \o k. 

When the height of a necessary embankment gets to be more- 
than 60 or 65 feet, a bridge or viaduct will be found cheaper, and 
the same measure, 60 feet, applies in case of tunnels, they being" 
cheaper at that depth than open cuttings. 

Under the head of laying out roads, something should be said 
of their width. Speaking only of such roads as are not apt to turn- 
into streets from their proximity to towns and cities, it is well not 
to make them too broad, for the less the width, the less the cost of 
construction and maintenance, and a good 23 feet road is much bet- 
ter than a poor one 40 or more feet wide. Each rod (16^ feet) in 
width adds two acres per mile to the road. An agreeable form of 
road is to have on each, or on one side of the same, a strip 5 or 6 feet 
wide, sodded, and then a sidewalk equal in width to one-eighth the 
width of the roadway. The intervening strip above mentioned, is 
planted with trees and at intervals of 200-250 feet furnishes storage 
places, 30 or 40 long, for the materials used in the road repairs. 
The width of first, second and third class roadways may be given 
as 26, 181^ and 13 feet, with a tendency during the last ten years 
to have none, except in the vicinity of cities, wider than 24 feet, 
and the rest correspondingly narrower. In view of the changes 
constantly going on in this country in the value and settlement of 



lO THE SCIENCE OF ROAD MAKING. 

land, it would probably be well always to lay out a road 50 or 60 
feet wide, but to build the road proper of the width above indi- 
cated. 

With all these rules and data in mind, the real work of actu- 
ally laying out the road on the ground and on a map is next in 
order, and this comes so entirely within the province of the civil 
engineer, and is a matter requiring so much explanation and study, 
that it cannot well be introduced within the limits of this treatise. 
It is in this part of the work that a little skill and labor well spent 
may be productive of very great saving in the cost of the whole 
work and it should not be left to the inexperienced or unskilful.* 
Making the Road-bed. 

Under this head are included, earthworks, drains, culverts, 
bridges, stay walls, etc., etc., all matters requiring a special kind of 
skill to construct properly. The writer believes it impracticable to 
write a book which shall at once be interesting to and therefore 
valued by the public, and of value to the professional man, and 
thinks an attempt so to do results always in a failure in both direc- 
tions. True to the determination expressed in the introduction, he 
proposes, therefore, to treat under this head mainly with those parts 
of the subject in which the public at large is most interested, for 
example, the data for the cost of earthworks, general information 
relating to drainage, bridges, etc. 

* Gillespie, in his treatise on "Roads and Railroads," gives two forcible 
instances of the amount those roads which might properly be called chance roads, 
can be improved by a road-maker of skill and understanding. An old road in 
Anglesea, England, rose and fell, between its two extremeties, twenty-four miles 
apart, a total perpendicular amount of 3,540 feet ; while a new road, laid out by 
Telford between the same points, rose and fell only 2,257 f^et ; so that 1,283 feet 
of perpendicular height is now done away with, which every horse passing over the 
road had previously been obliged to ascend and descend with its load. The new 
Toad is besides two miles shorter. The other case is that of a plank-road built in 
the State of New York, between the villages of Cazenovia and Chittenango. Both 
these villages are situated on Chittenango Creek, the former being eight hundred 
feet higher than the latter. The most level common road between these villages, 
rose, however, more than 1,200 feet in going from Chittenango, to Cazenovia, 
and rises more than four hundred feet in going from Cazenovia to Chittenango in 
spite of this latter place being eight hundred feet lower. That is, it rises four hun- 
dred feet where there should be a continual descent. The line of the plank- road 
laid out by George Geddes, civil engineer, ascends only the necessary eight hundred 
feet in one direction, and has no ascents in the other, with two or three trifling 
■exceptions of a few feet in all, admitted in order to save expense. The scenes of 
similar possible improvements are scattered all over this and the rest of the States ; 
and these facts are still more or equally to be borne in mind in laying out new roads, 
where the ounce of prevention may take the place of the pound of cure. 



THE SCIENCE OF ROAD MAKING, 



II 



Earthworks. 

The basis of all values is the daily wages of a common unskilled 
laborer, and in the data given below, this figure, whatever it is from 
time to time and in various places, must be taken as unity, or the 
standard measure. 

The cost of earthworks may be divided into three parts — (i) cost 
of loosening the earth, (2) cost of transport, and (3) cost of forming 
the transported earth into the desired shape. The cost of the first 
part depends materially on the kind of earth to be handled. The 
cost of the second, mainly on the distance the earth is to be moved. 

We find by experience, that in digging and loading or throwing 
5-10 feet horizontally with a shovel, we obtain for different mate- 
rials the results of the table on the next page. 
Transport of Earth. 

Throwing with a shovel, — This is to be done only from 5-12 
feet in distance or from 5-6 feet vertically. To throw 5 fv^et verti- 
cally, costs as much as 12 feet horizontally, that is to say, if 30 feet 
horizontally cost per cubic yard, one day's wages divided by 8.4 
the same distance vertically will cost about 21^ times as much, or 
more exactly, one day's wages divided by 3.5, whence is seen the 
economy of using windlasses, etc., instead of "stages,**! in shovel- 
ing earth vertically. The table gives the cost of shovelling earth 
certain distances, expressed in the number of cubic yards a laborer's 
day's wages will pay for. 



Distance of 
Throw in Feet. 


\ 

> 


Whether done at 
one operation, or 
by means of so- 
called "stages." 


Number of cu. yds. 
which can be trans - 
ported at the cost of 
one laborer's day's 
wages. 


Remarks. 


O-IO, . 


Horizontally, 


No " Stages." 


23.5 




10-20, . 


it 


I stage. 


12.6 


\ Wheelbarrow 
1 cheaper. 


20-30, . 


(( 


2 stages. 


8.4 


0-5. . 


Vertically. 


No stages. 


14. 1 




5-10, . 


" 


I stage. 


8.8 





fBy a " stage" is meant the operation of one shoveller lifting and throwing what 
another has thrown in front of him. 



12 



THE SCIENCE OF ROAD MAKING. 



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psppB sq 6} ^unoiuv 



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THE SCIENCE OF ROAD MAKING. 



n 



Wheelbarrows. — The usual distance of transport suitable for the 
use of wheelbarrows is 100-200 feet. In exceptional cases it maybe 
more, but perhaps never above 500 feet and then only for mode- 
rate quantities. In going up hill, the greatest inclination is to be not 
more than i m 10, and a man can push only ^ as much on this in- 
clination as on a level. 3 feet vertical transport costs as much as 
90-100' horizontally. Whenever possible, planks should be laid for 
the wheel-barrows to run on. The best timber for this purpose is 
beechwood and the cost of keeping such planks is only about -^ or 
-^ per. cent, of the cost of transport per cubic yard. 



Distance of Transport in Feet. 



trips per 

n hours, 

one man 

and one 


-^3 


ubicyds. 
be trans- 
le cost of 
r's day's 


er of 
of te 
ewith 
xrrow, 
ad. 


Ill 


erofc 
;hcan 
edattl 
labore 
es. 


umb 
day 
mad 
atb 
tolo 


%n 


umb 

whi< 

port 

one 

wag 


7\ 


^ 


iz; 


120 


^% 


23.5 


1 10 


2K 


16.9 


100 


2>^ 


14.4 


98 


■^Yz 


13.8 


96 


^Vz 


13.3 


94 


'^Yz 


12.8 


92 


^Yz 


12.4 


90 


^Yz 


12.0 


88 


^Yz 


II. 6 


86 


'^Yz 


II. 2 


84 


'^Yz 


10.9 


82 


'^Yz 


10.5 


80 


^Yz 


10.2 



10-20, 
20-50, 

50-70, 

70-100, 
100-150, 
150-200, 
200-250, 
250-300, 
300-350, 
350-400, 
400-450, 
450-500, 

500-550, 



Patent Portable Railroad and Hand-Cars. 
These have lately been introduced in this country, and appear to 
be coming into general use and favor. The company owning this 
improvement, as it seems to have a right to be called, claim, that by 
means of their track and cars, which can be used everywhere that a 
wheel-barrow or a horse-cart can go, and in a great many places 
where these vehicles cannot go, they affect a very large saving, as 
much in some cases as f of the cost by the other means of transport. 
There are no data published as yet to make tables from, similar 
to the foregoing ; from the company's pamphlet, however, one given 
case which occured on Staten Island in 1867, may be analyzed and 
tabulated as follows: — 



H 



THE SCIENCE OF ROAD MAKING. 



Distance of transport, in feet, . . . • . 550 
Number of trips per day often hours, with one man at 

two cars, and two to load, . . , . , 150 

Contents of car in cubic feet, ..... li«34 
Number of cubic yards which can be transported at the 

cost of one laborer's day's wages, . . • • 60 

One-Horse Carts. 
The table for this kind of transport may be stated about as fol- 
lows. I foot vertical costs as much as 14 horizontal. 





made 
hours, 
y four 

load, 
r trip. 


"K . 


icyds. 
trans - 
e cost 
day's 




a|§s^ 


'^1 


i-^^-s 


Distance of Transport in feet. 


'S's^..^ 


or, 


•Ss^g 




o> of 

per day 
assumi 
minute 
dump, 


^3 


umber 
which < 
ported 
of a lab 
wages. 




;? 





P? 


300 


86 


8 


17. 1 


500, 


67 


8 


13.6 


1,000, 


43 


8 


8.6 


1,500 


31 


8 


6.4 


2,000, 


25 


8 


5.0 


2,500, 


21 


8 


4.3 


3,000, 


18 


8 


3.6 



Ox-cart transport is 10 or 12 per cent, cheaper than the above, but 
takes more time. 

Other methods of transport, such as horses or engines on tem- 
porary tracks, would hardly ever be applied to road-building, but 
belong more properly under the head of railroad construction. 

, Shrinkage. 

In calculating the cost of earthworks, the so-called shrinkage of 
earth must not be overlooked. Earth occupies on the average -^-^ 
less space in embankment than it did in its natural state, 100 cubic 
yards, shrinking into 90. Rock on the contrary, occupies more 
space when broken, its bulk increasing by about one-half. 

The shrinkage of gravelly earth and sand may be taken at 8, of 
clay 10, loam 12, surface soil 15, and of "puddled " clay 25 percent. 
The increase of bulk of rock is 40 to 60 per cent. 



THE SCIENCE OF ROAD MAKING. 



To make use of all these data in calculating the probable cost of a 
piece of road, there are of course still wanting the equally essential 
factors which give the number of cubic yards to be dug and moved 
and the distance of transport. These are got from the plan, profile 
and cross-sections of the proposed work, an engineer's knowledge 
being requisite to make the necessary drawings and calculations. 

Drains and Culverts. 
The drainage of roads is of two kinds, surface and sub-drain- 
age. The first provides for a speedy removal of the rain-fall on 
the surface of the road and the cutting and embankments on which 
it is carried; the second, for the removal of that part of the rain- 
fall which nevertheless does penetrate into the body of the road- 
covering. With a perfect sub-drainage the winter's frost, having no 
water to act upon within the body of the road, is robbed of its great 
power to destroy the same, and it also prevents the road-surface from 
becoming soaked and thence destroyed in the summer. The need 
of surface drainage is self-evident. This last named is to be pro- 
vided for at this stage of the building of the road, the sub-drainage be- 
ing more properly a part of the building of the road-covering or top. 
For this purpose ditches, one on each side generally, are absolutely 
necessary, both when the road is on a level with the surrounding 
country and when it is in a cutting. They may become necessary 
also in the case of embankments : for example, when an embankment 
is built across wet ground. Where these side ditches cross under 
the embankment we have a culvert: also whenever any small valley, 
having a constant or intermittent stream of water, is crossed by such 
an embankment. It is very bad policy to make such culverts of 
wood, unless indeed they are so situated as to be constantly under 
water; the cost of replacing them after the embankment and road 
has been built over them is disproportionately great. They should 
be made of stone, or brick; lately vitrified stone-ware, or cement 
drain-pipe, oval or egg-shaped, has been used to advantage in their 
construction. 

All ditches, drains and culverts should have a fall throughout 
their entire length. Their size will depend on the amount of water 
they may be expected to carry, and this again on the rain-fall that 
wiay occur on the area which they drain. Extraordinary showers 



l6 THE SCIENCE OF ROAD MAKING. 

have occurred of 2 inches in half an hour but only over a very limited 

area, and 2 inches in an hour may be taken as a large allowance. 

This is the basis of the Central Park drainage calculations, and is 

larger than usually taken, none too large however for safety. 

The determination of the proper width and height of culverts, 
that will enable them to pass the requisite quantity of water with- 
out damming it up, is a question in practical hydraulics, easily enough 
settled, in cases of doubt, by the proper gaugings and observations 
made upon the spot, but which is answered only in a very crude 
and imperfect manner by any general rules that may be given. 
And yet it may prove a very important question at times. There 
is now (1877) pending in Massachusetts, a suit for damages, that may 
involve claims to the amount of rising half a million dollars, in which 
one great centre of attraction is nothing but a simple railroad culvert, 
and the question : Was it as large as it ought to have been ? and the 
^writer passes every day, when at home, by a culvert, which for some 
150 or 200 years has dammed the waters of a brook back about 3 
miles, from i ft. to say 20 in. at the culvert vertically, and done this 
right along two or three times per annum, and at the present time 
it contributes in this manner, more than its proper share towards the 
flooding of about 500 cellars. These two cases may serve to call 
attention to the great damage that may accrue from making culverts 
too small, and to show whence comes the rule : in cases of doubt, 
make the culvert plenty large enough. The following rough ancf 
lapproximate rules for determining the quantity of water that a cul- 
vert will be called upon to pass through it, are taken from a Ger- 
man pocket-book for road engineers. Compute the cubic feet pel 
second from the drainage area that lies above the culvert, and, foi 
the different lengths of valley from the corresponding rain-falls 
per hour. (The rain-fall is given in inches per hour, instead of in 
decimals of a foot per second, only for the purpose of avoiding the 
j)rinting of long decimals). 

LENGTH OF VALLEY IN MILES. INCHES PER HOUR. 

2 . 5 or less, i . 2 

2.5 to 5. 0.75 

5. " 7-5 0.45 

7.5 "10. 0.30 

10. or more, 0.15 

As culverts grow larger and wider with the amount of water they 

-are to pass under the road, they develope finally into 

Bridges. 
Bridge-building is a life's study, taken by itself, and in some of 
its parts it is not half appreciated and known as yet among the pub- 
lic. Prominent among these is beauty of design and appropriate- 
ness to the situation. There is perhaps nothing else that will so 



THE SCIENCE OF ROAD MAKING. 



17 



much improve the appearance and attractiveness of a road as a 
beautiful bridge. So also in cities w^e find that a street vs^ill of its 
own accord, seemingly, improve in appearance, v^hen a good and 
handsome bridge has been erected on its line, the owners and build- 
ers of the adjoining buildings taking the bridge for their pattern and 
model. Nor must it be supposed that a handsome bridge must ne- 
cessarily cost more than an inappropriate or homely, uncouth struct- 
ure ; it need never be the case. Very often the chief beauty of a struct- 
ure lies in the fact of its carrying the most with the least expenditure of 
material. No one bridge is proper in every situation, and herein 
many mistakes are made. The correct way to build a good bridge, 
is the same or a similar way to that followed in first-class buildings, 
namely, to have plans drawn for the same and receive estimates 
and offers to build according to these plans. It is not well to allow 
the offices of designer, superintendent and contractor to be united in 
one person or firm, and is expecting too much from human nature. 
Making the Road Surface. 

There are two subordinate kinds of road surface, if the term road 
can properly be applied to them, namely, that of foot and riding 
paths ; these may be disposed of first, before proceeding to the more 
important consideration of the road surfaces proper, those used by 
vehicles of all descriptions. 

Footbaths. — For the surface of a foot path little solidity is ne- 
cessary, except in city sidewalks, which are not supposed fo be treat- 
ed of here, but we do need a material that shall become and stay 
compact soon after it is laid. Coarse sand, screened gravel, stone 
chips and dust, make good paths ; should these materials be too free 
from any earth or clay, a little of the same may often be added to 
advantage to act as a binding material. Wherever the ground un- 
derneath the surfacing is not porous or likely to remain porous 
enough to let all the water that may soak through drain away, a 
layer of such porous material must be filled up before the top sur- 
face is put on. Oyster shells, or large stone chips, gravel stones 
or pebbles, etc., make a good foundation of this sort. The top cover- 
ing should have a slope, best in both directions from the centre of 
the path towards each side of about i in 16; the thickness of the 
foundation course to be 3 to 5, and that of the top 3 to 4 inches. 



1 8 . THE SCIENCE OF ROAD MAKING. 

No gravel path, or side-walk, will afford good walking at the 
season of the year when the frost is coming out of the ground. 
Carting on more gravel is in vain ; it is often no better than mere 
foolishness. If village communities will get this idea firmly into 
their minds, and, instead of a fruitless struggle against the laws of 
nature and of gravel, will build stone screening sidewalks with a 
good foundation course underneath, as above described, or else some 
sort of hard sidewalk covering, they will save themselves much ex- 
pense, many muddy feet, and no small amount of consequent and 
annual discontent, not to say profanity and ill feeling. 

Heavy rolling and wetting down will save much time in finish- 
ing the whole process; the roller should be used unsparingly and 
throughout the whole construction of the path, on the foundation, 
as well as on the top. 

Riding-Paths. — From the nature of the travel these are intend- 
ed to acommodate, their surface must be of a peculiar kind. Inas- 
much as a horse, in galloping, tends to throw the soil he treads on 
backwards with his hoofs, the surface must be kept somewhat 
loose and soft to make riding on it easy and agreeable. 

This requirement makes it impossible to have any slope on the 
surface (the loose material would wash away if there were any), and 
hence we must rely here wholly on sub-drainage, and not attempt 
any surface drainage. The top is made of coarse sand, free from 
clay or other binding material, laid on two and one-half to three 
and one-half inches thick, and spread out level. Under this is a 
solid foundation, about four inches thick, made of coarse gravel and 
clay, and having a slope of about i : 20, so that the water will run 
oflf along its top surface to either side, where it must further be dis- 
posed of by drains or ditches. In case of riding paths too wide to be 
so simply built, the sketch shows the method to be used. The 



foundation is made in several slopes, at the lowest parts of which 
are placed drains, running in the direction of the path, but commu- 
nicating from time to time with the sides of ditches or drains. 
Should, however, the ground underneath be porous enough, the 
drains may be dispensed with ; and if in their stead holes be dug 
along the lowest lines, marked fl, a^ and these filled with large 
stone, the water will, through them, drain away into the ground. 
Roads, — To make a good road surface is a very simple operation 



THE SCIENCE OF ROAD MAKING. 



If 



after it is only once understood, and, the fundamental principles 
thereof once comprehended, they can hardly be forgotten. Every- 
thing connected with the construction, the use and maintenance of 
roads, was, in times past, before the invention of railways, the sub- 
ject of exact observations and experiments, many and varied in char- 
acter. 

Old engineering works that treat of road-making are on this 
account excellent reading upon this subject at the present day. 
Upon road construction no less than upon the need of better road- 
legislation. Some, perhaps the most of the evils we suffer, in the 
shape of bad common roads, are merely the result, the necessary 
consequence of our bad systems of common road management, 
which are derived from our antiquated legislation upon that sub- 
ject. Legislation of thiskind has changed but little in a hundred 
years, and is producing the same evils to-day, that it did a hundred 
years ago. Hence it is explainable, that the complaints concerning 
bad roads, and bad road management which we read in books of 
fifty and of sixty years ago, sound to our astonished ears as though 
they had been written but yesterday. On this subject may be 
consulted: The life of Telford, the great English road builder, 
who died some fifty years ago, (also among " The Lives of the 
Engineers," by Samuel Smiles), " A treatise on Roads," by Sir H. 
Parnell, 1833, and other works of former date. 

Besides this, we have the results of a great number of years of 
experience in older countries, and there would seem to be little to 
invent, but much to learn, in this branch of construction. Though 
less progressive than other branches, there are nevertheless im- 
provements in road-making, especially in road-making machinery 
and tools ; and no treatise on this or any other living subject can be 
considered complete in a very few years after it is written. 

Ancient roads were made with a surface as nearly resembling the 
solid rock as possible. So, in China, roads were made of huge 
granite-blocks laid on immovable foundations. In time these be- 
came worn with ruts, especially in the joints or seams of the stones, 
and the surface generally so smooth that animals could hardly 
stand, far less trot on it. They are now for the most part deserted, 
and left to be covered by land-slides, etc., to one side of the new 
roads of travel. 

The invention of McAdam consisted in having no large stone at 
all on the roadway, but having it all pounded into fragments and 
spread over the road-bed. This has, without fear of efficient con- 
tradiction or shadow of doubt, been proved by trial to be a worth- 



20 THE SCIENCE OF ROAD MAKiNG, 

less proceeding, though at one time popular, ainl eve© now too 
often done, either from ignorance or laziness. The separate frag- 
-ments of stone, have no bond among themselves, are liable ^o sink 
^into the underlying ground or road-bed, evenly or unevenly as' ** 
may chance, more in one place than another, and thus never, come 
to rest or to an even top surface. Between these two extremes of 
an ancient Chinese solid rock road and that of McAdam, lies the 
true principle of road-making, which consists in giving every road 
two component parts ; one, — the foundation, — to be solid, unyield- 
ing, porous, and of large material; the other— the top surface — to 
be made up of lighter material, and to be made to bind compactly 
and evenly over the rough foundation. This constitutes the whole 
principle to be followed; and let it be repeated, that to dump the 
road material directly on the ground, without first preparing a 
foundation for it, as is so frequently done, is a waste of time, labor 
and materials, by no possibility resulting in a good road. On this 
one fundamental idea, which is never abandoned, however, there 
are a number of variations. Besides these roads, whose character- 
istic is the foundation they are all built on, we have paved roads, or 
pavements, of a great many kinds, and roads with trackways, also 
of various kinds. 

Foundation Roads. 

The roads of this kind, with macadam for the top surface, are 
called Telford roads by English writers, from Telford, who first 
built them in England. The Central Park " gravel roads " belong 
under this head, gravel taking the place of the macadam of the Tel- 
ford roads. These foundation roads are of far greater importance 
than any other kind for State, county or town roads, also for parks 
and driveways. The top surface of all these roads must have a 
certain inclination, to cause eflficient surface drainage. Various 
authorities give various rules for the amount of this inclination or 
side-slope. It would seem just that it should depend on the nature 
of the top covering, being less for more solid than for looser or 
softer materials, and also on the grade of the road. 

In Baden, one of the smaller German States, but which is 
worthy to be taken as a model in matters of road-building, and in 
France, the rise at the centre is given as ^--^ of the width of the 



THE SCIENCE OF ROAD MAKING. 21 

taad, according to the nature of the material ; that is, inclinations of 
I in 20, and i in 30. The rules in Prussia prescribe inclinations of 
1 in 24 for roads falling more than 4 in a hundred; i in 18 for roads 
on a grade of between 2 and 4 in a hundred; and i in 12 for those 
on a grade of less than 2 in a hundred. When first built, the cen- 
tre should be made some four inches too high, to allow for after 
settling. 

Macadam Top. — The cross-section of such a road is about as 

drawn; *™° |^^^^^^^^^^^^^^^ the 

thickness of the foundation b^=za., the thickness of the top covering 
at the centre, and is six, four or five and three and one-half inches 
in thickness for first, second and third class roads. If the stone for 
the foundation — for which most anything will do, and that kind 
should be taken which is cheapest to procure — happens to be got 
out cheapest in larger pieces than the above dimensions, it will do 
no harm. This foundation course is sometimes set so as to present 
an inclination on top, and the cover then put on of a uniform thick- 
ness over the whole breadth. This is perhaps best, but is some- 
what more expensive. It will do, in nearly all cases, to set the 
foundation course on a level, or as near so as the stones will allow, 
■nd then make the top crowning, by making the covering say 
three-quarters of an inch or an inch less thick at the edges than in 
the centre. The stones forming the foundation should not be set 
in rows, nor ever laid on their flat sides, but set up on edge and 
made to break joints as much as possible; that is, set up irregularly. 
After they are set up, the points that project above the general level 
may be broken off, and the interstices generally filled with small 
stone. More or less care and work are necessary in this part of 
the operation, according to the importance of the road and the 
depth and character of the material used for the top covering. To 
roll the road at this stage is to be recommended ; afterwards it be- 
comes a requisite. The point never to be lost sight of, is that this 
foundation course must remain porous, must be pervious to water, 
go that all rain-water that shall soak through the top covering will 
find, through it, means of escape to the ground underneath ; thence, 
•ccording to the nature of the subsoil, it is left either to soak into 
the ground, or must be further led away by appropriate drains. 



22 



THE SCIENCE OF ROAD MAKING. 



Of very great importance is the material used for the top or 
road covering. In the order of their value for macadam, we have. 
I. Basalt. 
II. Syenite and Granite. 

III. Limestones. 

IV. Sandstones. 

It will be evident, that a much greater quantity of the soft 
stones would be required to repair a certain road, than of a harder 
kind, and on a road lying out of the way of a hard stone quarry or 
deposit, the question will arise which is cheapest, to pay more for 
the raw material and get good stock, or pay less and use the 
worse? There have been some interesting results in places where 
this matter has been the subject of experiment, continued for a 
number of years. Thus, on a road in Baden which was formerly 
macadamized with rock costing only fifty cents per cubic yard, \% 

Fig. 5. Perspective View of New Pattern Crusher. 




was finally found cheaper, to take harder rock from a distanot 
costing one dollar and seventy-eight cents per cubic yard, the salv- 
ing being both in less quantity of material used and less labor y^» 
quired in repairs. Just where the limit is, must be found in each 



THE SCIENCE OF ROAD MAKING. 23 

case by long continued experiment, which is well worth the trouble 
to make, both to save expense and also to have the best possible 
road, the harder material making a road better at all times, at the 
same or less cost. After the right kind has been determined, none 
other should be mixed with it, and should any inferior piece acci- 
dentally or designedly get into the stock to be broken up, it should 
be picked out and thrown aside. The stone is broken up into 
macadam, either by hand or machinery. Wherever any consider- 
able quantity of macadam is in present or future demand, a stone- 
breaker is certainly a saving over hand-labor, though it is difficult 
to draw a line exactly, where hand-labor or machine labor is 
cheapest. Probably no town that pretends to keep thirty or forty 
miles of road in good repair, ought to be without one of these labor- 
saving machines. Those most in use are made by the Blake Crusher 
Co., of New Haven, Conn., and the following is taken from their 
circular. 

Their machine has been patented in the United States and in 
several foreign countries, and is now in use in almost every coun- 
try on the globe. It is simple and compact, and being complete in 
itself, requires no extraneous support or fixtures. Two patterns of 
the machine are now sold: the old, or "Lever Pattern," and the 
new, or " Eccentric Pattern." The figures, and following descrip- 
tion, refer to the last named machine. Fig. 5, is a perspective view 
of the machine, entire. The frame which receives and supports all 
the other parts, is cast in one piece, with feet to stand on the floor or 
on timbers. These feet are provided with holes for bolts, by which 
it may be fastened down if desired; but this is unnecessary, as its 
own weight gives it all the stability it requires. The flywheels 
are on a shaft which has its bearings on the frame, and which be- 
tween these bearings, is formed into a short crank. On the same 
shaft is a pulley, to receive a belt from a steam-engine or other 
driver. 

Figure 6 shows a side view or elevation of the parts in the 
machine in place as they are presented to view through the side 
of the frame. The circle D, is a section of the fly-wheel shaft, 
which should make from 225 to 250 revolutions per minute. 
The circle around D is a section of the eccentric. F is a pit- 



24 



THE SCIENCE OF ROAD MAKING. 



man or connecting rod, which connects the eccentric with the tog- 
gles G, G, which have their bearings, forming an elbow or toggle 
joint. H, is the fixed jaw; this is bedded in zinc against the 
ends of the frame i^ inch thick. P, P, are chilled plates against 
which the stone is crushed ; when worn at the lower end they can 
be inverted, and thus present a new wearing surface. The cheeks 
I, I, fit in recesses on each side, and hold the plates in place; by 
changing the position of the cheeks from right to left, when worn, 
both will have a new surface. J, is the movable jaw; this is sup- 
ported round the bar of iron K, which passes freely through it, and 
forms the pivot upon which it vibrates. L, is a spring of India 
rubber, which is compressed by the forward movement of the jaw, 

Fig. 6. Sectional View of New Pattern Crusher, with Parts Lettered. 
FOR Convenience in Designating Pieces Wanted for Repairs. 




and aids its return. M, M, are bolt holes. B, is the fly wheel. C, 
is the driving pulley. Every revolution of the crank causes the 
lower end of the movable jaw to advance towards the fixed jaw 
about one-fourth of an inch and return. Hence, if a stone be 
dropped in between the convergent faces of the jaws, it will be 
broken by the next succeeding bite ; the resulting fragments will 
then fall lower down and be broken again, and so on until they 
are made small enough to pass out at the bottom. The readi- 
ness with which the hardest stones yield at once to the influence of 
this gentle and quiet movement, and melt down into small frag- 



THE SCIENCE OF ROAD MAKING. 



25 



ments, surprises and astonishes every one who witnesses the opera- 
tion of the machine. 

It will be seen that the distance between the jaws at the bottom 
limits the size of the fragments This distance, and consequently 
the size of the fragments, may be regulated at pleasure. A varia- 
tion to the extent of ^ths of an inch may be made by turning the 
screw-nut W, which raises or lowers the wedge N, and moves the 
toggle-block O forward or back. Further variations may be made 
by substituting for the toggles G, G, or either of them, others that 
are longer or shorter; extra toggles of different lengths being fur- 
nished for this purpose. 

This machine may be made of any size. The builders have pat- 
terns for some 13 different sizes on hand at the present day. Each 
size will break any stone, one end of which can be entered into the 
opening between the jaws at the top. The size of the machine is 
designed by the size of this opening; thus, if the width of the jaws 
be ten inches, and the distance between them at the top five inches, 
we call the size 10x5. '^^^ following table shows the principle 
facts that relate to the sizes of machines that are used, generally, 
for the making of road-metal. 



No. 


k 

S 
I 




III 




•I 


Extreme Dimensions. 


Driving Pulley. 


u 

2 

Oh 


1^ 






Length 


Bre'dth 


Height. 


Diam. 


Face. 


6i% 




Inches. 








ft. in. 


ft. in. 


it. in. 


ft. in. 


inch. 








2 


10X7 


Five, 


4339 


8000 


5 ZVz 


38 


4 5 


2 


VA 


250 


6 


$goo 


*3 


15X5 


Six. 


4700 


9100 


8 7 


5 


5 


2 4 


8 


180 


9 


1035 


*4 


15X7 


Six. 


5890 


10490 


8 7 


5 


5 


2 4 


9 


180 


9 


1125 


5 


15X9 


Seven. 


6436 


13360 


6 5 


5 


5 II 


2 6 


9 


250 


9 


1234 



Note. — ^The amount of /rt?</«c/ depends on the distance the jaws are set apart, and the 
speed. The product given in the Table is due when the jaws are set i i-a inches open at thy 
bottom, and the machine is run at its proper speed and diligently fed. But it will also vary 
somewhat with the character of the stone. Hard stone or ore that breaks with a snap will go 
through faster than Sand stone. 

To make good road metal from hard compact stone, the jaws 
should be set from ij^ to \% inches apart at the bottom. For 
softer and for granular stones they may be set wider. 



26 THE SCIENCE OF ROAD MAKING. 

A cubic yard of stone is about one and one-third tons. 

In getting an engine to drive one of these Crushers, it is ad- 
visable to have one of greater power than just what is stated in the 
table as required. It is much more economical to use 9-horse 
power from a 12 or 15 horse, than from a nine or ten horse engine. 
The machine may be driven by any power less than that given in 
the table, yielding a product per hour smaller in the same pro- 
portion. 

10x7 — (No. 2.) Will take in a stone 10 inches wide and 7 
inches thick, and is quite an effective machine. It may be set to 
break to any size down to ^ inch, and can be used for the same 
purposes as the 10x5, but receiving pieces two inches thicker is 
preferred in many cases. It will do a good deal in the preparing 
of road metal. It is one of the most salable sizes. 

15x5 — (No. 3). This machine takes in a stone only 5 inches 
thick, but being 15 inches wide is a more effective machine than 
the 10x5, but is used for same purposes when a larger product is 
required. 

15x7 and 15x9 — (Nos. 4 and 5). These are the sizes most 
salable, and best adapted to general purposes. They are the sizes 
almost uniformly used for breaking stone for McAdam roads and 
Ballasting railroads and for concrete. They are also used exten- 
sively at smelting furnaces — also at copper and other min-es, to 
take the product of the coarse breakers and reduce it to proper size 
for feeding under the stamps. 

When broken by hand and for country roads, the stones should 
be broken on the storage places already mentioned, which are to 
be established along the side of the road every 200 to 250 feet. 
The laborer is not to pound the stones on a heap of such, but to 
use one large stone as a sort of anvil to break the others on. He 
is to use a light hammer, except for pieces containing more than 
four or five cubic feet, and may use a ring with a handle attached 
to hold the stone he desires to break. 

In order that the road shall get an even surface, the macadam 
must all be of one size, and the proper size for the macadam de- 
pends on the degree of hardness of the rock. If too small, it turns 
to dust; if too large, the top will not pack even. The size is regu- 



THE SCIENCE OF ROAD MAKING. 



27 



lated by the use of a ring as a gauge,— every stone being obliged 
to be capable of falling through this ring in any direction it may be 
dropped. Hard stones should be one to one and a quarter, softer 
ones one and a half, and the softest two inches in diameter. Larger 
sizes give less perfect roads. In loading and otherwise handling 
macadam, a many and close-pronged pitchfork should be used 
instead of a shovel, so as not to mix in any earth or sand, and so 
sift out the stone dust and chips. 

The macadam being properly prepared and loaded up, it is 
spread over the foundation in two or three successive layers. 
Each layer should be rolled, but the top and last one must be 
rolled to make a good road. Nor will rolling alone do the work. 
Two other helps are needed : the use of a building material, to act 
as a cement between the broken stone, and sprinkling. It is diffi- 
cult to prescribe in words just what to use as binding material, and 
just how much to sprinkle and roll; common sense will in most 
cases be a safe enough guide. In the macadamized streets of Paris 
the rule is to roll till a single piece of macadam placed under the 
roller, will be crushed, without being pressed into the road surface. 
Gravel somewhat mixed with clay by nature, but not too much, 
is probably best as a building material. Clean coarse sand is very 
good. Other substances will do, where it would cost too much to 
procure either of the above. 

A late writer in the "Journal of the Society of Civil Engineers 
and Architects," at Hannover, calls attention to the practice in Bo- 
hemia of making foundation roads by setting first the foundation 
course, spreading a thin layer of the binding material on that, and 
the broken stone on top of this again. The subsequent rolling has 
the effect of forcing the binding material, slowly and gradually, 
from beneath upv*^ards into and through the broken stone. The 
writer states that he himself has tried a system of road construction 
that consists of a combination of the two methods hitherto used, 
with good results, namely : first, a foundation course, a thin layer 
of binding material on this, then the broken stone, another thin 
layer of binding material, and then wet down and roll. 

The subject of rollers is one demanding some attention. In 

general, people are apt to over-estimate the value of a roller with 

respect to its weight. It will be evident on reflection that a roller 

should be as heavy per inch in length of roller, as a loaded wagon 

wheel is per inch of tire ; or, in other words, if we have a wagon 



28 THE SCIENCE OF ROAD MAKING, 

with tires two and one-half inches wide and on each wheel a load 
of say one ton, the roller should weigh two-fifths ton for every 
inch in length, or a roller three feet long should weigh about four- 
teen and one-half ton&, or else a wagon as above described would 
exercise more pressure on the road-bed per square inch than the 
roller, and consequently would cut into the rolled surface and pro- 
duce ruts. 

The proper width of tire, or proper load upon any vehicle, for 
a given width of tire, is a question that occasionally attracts atten- 
tion. Bokelberg, a good German authority on the subject, in an 
article in the "Journal of the Society of Civil Engineers and 
Architects," at Hannover, 1858, comes to the conclusion that for 
four-wheeled vehicles, upon a broken stone road, the loads should 
vary with the widths of tires, as follows : 

WIDTH OF TIRES. INCHES. LOAD IN LBS. 

2 to 3 5,000 to 6,600 

3 •' 4 6,600 ** 8,800 

4 " 5 11.000 

5 " 6 13000 

6 '• 7 15,000 

7 and over. 16,500 

Further conclusions are: that the best width of tire, measured 
when they are new, for the transportation of freight, is from four 
to seven inches ; this width being best for the easy traction of the 
load no less than for a minimum wear of the road surface. To 
make the tires wider than seven inches does not diminish the force 
required to move the load, and unnecessarily increases the dead 
weight of the wagons. 

Road-rollers are of two principal kinds: those pulled by horses 

and those propelled by steam. The latter are for many reasons 

the best. In the first place they can be made as heavy as desired, 

without proportionally increasing the cost of propelling them, and 

being self-propelling, the only track they make is that of the roller, 

whereas with horse rollers, the hoof-marks of the horses are a 

great objection. Then again in the amount of work they will do 

at a certain cost, they excel horse rollers. They may be briefly 

described as a sort of locomotive mounted on three or four very 

broad and heavy wheels, these latter being the road rollers. 

An excellent pamphlet on the subject of steam road-rollers is 
the " Report on the Economy of Maintenance and Horse-draught 
through Steam Road-rolling," by Frederick A. Paget, E. & N. F. 
Spon., 1870. Readable articles on the same subject are: "Steam 
Road-roller," Engineering, Oct. 4, 1867. "Paris Kind of Steam 
Road-roller," Engineering, May 7, 1869 " Cost of Operating 



THE SCIENCE OF ROAD MAKING. 



29 



Steam Road-roilers," Engineering, June 18, 1869. "Good Steam 
Road-roller," Engineering, Jan. 14, 1870. "Economy of Steam 
Road-rolling, Engineer, April i, 1870. "How to use the Road- 
roller during alternate Thawing and Freezing," Annales des P. 
& C, 1877, p. 125. In the spring and fall on finished roads, and 
occasionally during the first construction or reconstruction of roads, 
the surface becomes sticky mud, and to roll the road at those times, 
or to travel on it, tears up the covering and spoils the whole. If 
at such times the roller be constantly sprinkled and kept wet while 
it is being used, it will shed the mud or road covering, instead of 
tearing it up, and will consolidate the road in a very superior man- 
ner. And this method requires less water (only about one gallon 
to one and a half gallons per 100 feet of travel) than the method 
formerly used under these circumstances of converting the sticky 
mud into liquid mud, by copiously wetting down the whole road. 

There are several varieties in use in France and England, and 

two at least of the English kind have been imported into this 

country, one for the New York Central park, the other for the 

Arsenal Grounds in Philadelphia. The cost of the Central Park 

steam road-roller made by Aveling & Porter, of Rochester, Kent, 

England, was about $5,000, set up in New York, and the amount 

of work it will do in one day at a running expense of $10, has 

been given as equal to that of a seven-ton, eight-horse road-roller 

in two days at $20 per day, or, in other words, it will do the same 

"work at one quarter the running cost and in one-half the time, of 

a first-class horse road-roller. 

Since 1870 many other steam road-rollers have been bought 
by various parties in the United States. Thus there is one owned 
by Daniel Brennan, a road contractor, in Orange, N. J. ; the city 
of New Haven, Conn., has run one with great success for several 
years; after many years of agitation on the subject, the city of Bos- 
ton now owns and operates a steam road-roller; and so on. 

The best horse road-roller of which the writer has any cogni- 
zance is the one shown by the annexed drawings in plan, elevation, 
and in perspective. 

(The town of Maiden, Mass., has built a horse road-roller, 
according to the plan here described.) 

It originates in Chemnitz, Germ-any, but can, of course be easily 

made by any machine-shop or foundry. The hollow roller is 

made of cast-iron, and is 'so arranged that it may be filled with 

water when it is to be used in heavy rolling; when not in use and 

-about to be moved from place to place, the water is allowed to run 



30 



THE SCIENCE OF ROAD MAKING. 




THE SCIENCE OF ROAD MAKING. 



31 



out, thus materially lessening the load. A circular cast-iron frame 
A, surrounds the roller, and carries the axle bearings of the same. 
The outside of this frame is turned to form a groove in which a 
strong wrought-iron ring is fitted in such a manner that it will 
turn easily around the former. This wrought-iron ring consists 
of two semi-circular parts, at whose junction the pole is attached 
on one side, and on the other an extension bar, carrying the bal- 
ance weight c, which may be shifted by means of the set clamp d^ 
or turned up by means of the hinge b. Pins going through the 
holes at ^, fasten this ring or allow it to be turned for the purpose 
of pulling the roller in the contrary direction, when required. 
The brake is shown aty,y, and consists of four wooden brake- 
blocks, attached by iron shoes to a bar behind them and having 
rubber packing between the shoes. The screws shown and the 
handles h^ are used to operate these brakes. The cranks /«, work- 
ing the screws «, operate the scrapers /, which are used to keep 
the roller clean in muddy weather. The frame A, is made heavier 
at o, so as to have increased weight there to balance the whole 
frame-work in turning around. The support ^, and the guide 
wheel ^, might be dispensed with. A great saving in time and in 
movements hurtful to the road is effected by making the frame 
circular as described, thus allowing the roller to be turned with the 
greatest ease. The dimensions are figured on the drawing. A 
roller of this kind four and one-half feet in diameter, and three 
and one-half feet long, and weighing some four tons when empty, 
would cost perhaps $560 to $600; one 5 ft. by 3 ft. 8 in., weighing 
about five and one-quarter tons (empty,) some $700 to $750. 
Leaving off the break, would diminish the cost about $50. 

Before leaving the subject of macadam top roads, it ought to 
be mentioned that a bed of rubble stone 10 or 12 in. deep, merely 
spread uniformly over the road-bed as a foundation, is better than 
nothing at all, but can never make the same quality of road as the 
rough paving described above. 

The following data are to be used in estimating the cost of the 
kind of road just described. Rough foundation paving, pieces 
5 to 6 in. long, filling up crevices and ramming the whole with 
hand rammers, costs, after the material has been brought to the^ 



J^ 



THE SCIENCE OF ROAD MAKING. 




i. 



THE SCIENCE OF ROAD MAKING. 



33 



spot, one day's work of a common laborer for every four square 
yards, this assuming that the paver gets one and two-thirds com- 
mon laborer's wages. Same kind of paving if set in sand will 
cost one day's work of a common laborer for every two and one- 
quarter square yards. 

These figures for the cost of setting rough pavement for a 
foundation course have been objected to by an American road con- 
tractor, as entirely too high, he claiming to set 20, and even 50 
square yards to a man per day. An explanation of these different 
figures probably lies in the phrase, " ramming the whole with 
hand rammers " ; in the general quality of the work done, etc. 
The writer's own opinion is, that no very fine work is necessary in 
the construction of the foundation course. Its duties are, to remain 
pervious, and not to settle unevenly. The same contractor above 
mentioned wrote, in 1870: " I put down, and keep in perfect order 
for a year from the time of completion, a 12-inch road (6 to 7 inch 
foundation, 5 to 6 inch surfacing) at a distance from the quarry of 
three miles (materials exclusively quarried trap rock), for $1.50 
per square yard; wages of men average $2.25 per day, and of 
transportation, $1.25 per cubic yard. This includes my profit." 

To make macadam by hand costs, for sizes from i J^ to 1 1^ in. 

of very hard rock, one day's work for every 0.6 to 0.44 cubic 

yards, for less hard rock, one day's wages will make 0.7 to 0.6 

cubic yards, and of soft rocks 1.76 to 1.17 cubic yards. 

In 1872 the estimated cost of crushing stone by the Blake 
machine ranged from 30 to 60 cents per cubic yard; to crush the 
same stone by hand, it was estimated would cost from $1.20 to 
$3.00 per cubic yard. 

To spread 14-12 cubic yards of macadam is also about a day's 
work. 

Gravel Top. — Instead of the macadam top described in the pre- 
ceding articles, screened gravel may be used. These roads are the 
favorite ones in Central Park, New York, and are probably the 
best road there is for pleasure drives. It is a matter of some doubt 
yet whether they do as well for heavy trucking as they do for 
light vehicles. The foundation for these gravel roads should be 
the same as the rough paving for the macadam road; some pieces 
were built in Central Park having a rubble stone foundation, but 
they are not recommended by their builders. The gravel to be 
"sed for the top must be selected with some care ; it should be of a 
hard kind of stone, clean, that is, free from clay, etc., of the right 



34 



THE SCIENCE OF ROAD MAKING. 




THE SCIENCE OF ROAD MAKING. 



35 



color, etc. It is put on in two layers, each rolled, and the top one 

made compact and firm, by spreading and mixing in some good 

binding material, sprinkling and rolling. There need be no fear 

of making a poor road by using the smoothest, most water-worn 

pebbles, free from all sand, etc., in making a road-top. The upper 

portions of the river Rhine are remarkable for the clean, smooth 

pebbles that form its bed to a very great depth. These pebbles 

are dredged up and used in road-building, making an excellent 

road-covering at a small expense. There are many miles of such 

roads in Baden and in the Bavarian Rhine Provinces. 

In gravelly soil all the materials that are needed for a good- 
road are frequently on the spot; they only need sorting out and 
re-laying. For this reason a common gravel sieve often consti- 
tutes the principal instrument, whose judicious use will make a 
good road out of a miserable string of ruts and cobbly elevations^ 
It would be only necessary to sift out and separate the soil under 
the road to a sufficient depth, into cobbles, coarse gravel, fine 
gravel and sand ; then replace them in the order named and with 
the proper thickness of layers of each; wet down and roll, and the 
result would be a good road. As regards the advisability of well 
constructing roads, the following, from the Bath (Maine) TimeSy 
of May II, 1870, is not without instruction. (The Waltham roads 
therein spoken of are also mentioned in the extracts from a report, 
which is printed in the Appendix) : " I will here submit a com- 
parison of the cost of our road, with those of the town of Wal- 
tham, noted for its good roads. Waltham has 51 miles of roads;; 
the expense, including everything, of maintaining their highways,, 
except sidewalks, for seven years previous to 1868, w^as $3,357 per 
year, or %66 per mile. In 1868, with 60 miles of road, including 
probably the building of 9 miles, the cost was $6,000, or $100 per 
mile. The city of Bath has not over 32 miles of roads. The 
average cost of repairs on our roads for the three past years is 
$10,153; not including the expense of sidewalk, $317 per mile. 
At this rate, if we reduce the cost of repairs of our roads to $100 
per mile, we could afford to hire money at 7 per cent, and expend 
$100,000 upon their permanent improvement, and it would be 
vastly cheaper to do so than to continue our present system." 

Keeping- Roads in Repair, — This subject properly finds its 
place here, being a matter of skill and a thing of debate only in 
the case of what we have called foundation roads; pavements and 
trackway roads, to be considered after this, need no special direc- 
tions as regards their repair or maintenance. 

After a road has been properly rolled, and the surface made 



36 



THE SCIENCE OF ROAD IIAKING. 




THE SCIENCE OF ROAD MAKING. 



37 



compact and smooth, it should always be maintained in that con- 
dition, no matter how great is the amount of travel on it. "A 
stitch in time saves nine," here as well as elsewhere. The ten- 
dency is to produce ruts; these gather water; this soaks up the 
road-bed and spoils the whole. The problem can be put in this 
way: To have a good road it is necessary that there be no dust or 
mud on the same, and that there be no ruts; therefore, remove the 
dust and mud as fast as they are formed, and fill up the ruts as fast 
as they are made. The whole matter is here in a nut-shell. It 
may be thought, at the first view^, that this is too expensive a sys- 
tem. Its principal beauty lies, however, in the fact that it costs 
less per mile of road kept one year than the pernicious system of 
annual or semi-annual repairs, as will be shown and proved. The 
above two rules — sweep off the mud and dust as fast as they are 
formed, and fill up the ruts and bad places with new material as 
fast as they appear — are all that is necessary to be carried out in 
order that there be continually a good road. Without continual 
repairs, there can be no such thing as a constantly good road — 
a proposition that cannot too often be repeated. By repairing a 
road annually, or twice a year, it matters not which, the result is, 
strictly speaking, a good road at no time during the whole year. 
The road is wretched just alter repairs; it becomes passable after a 
while, and deteriorates from that day forward, until it is again made 
wretched; and so on, ad Jinitum., according to the present, only 
too commonly followed system. By the other method is offered 
us a road as smooth as a floor, year in, year out, and, let it not be 
forgotten, at a less expense. 7 

A French engineer, named Tresaguet, was the first, in 1975, ^^ 
call attention to this proper method of making road repairs. His 
system — the above described one — was adopted in Baden in the 
year 1845, ^^^ ^^^ been long in universal use in all the active 
European countries. The two tables below give, the first, the 
actual average quantity of road macadam used per mile of road in 
Baden to make the repairs in one year, and show the decrease after 
1845. The second gives, in the first column, the cost of materials 
and labor required to repair one league for one year according to 
the old way, — this column being calculated for the years following 



38 



THE SCIENCE OF ROAD MAKING. 



J 845 from the cost of the preceding years, and allowing for the 
increased value of labor and materials, — while in the second col- 
umn we have the actual cost, as it was with the system followed 
at the time : 

Table I. 



YEAR. 


Cubic yards used per 
mile in one year to re- 
pair roads. 


1832, 

1839. . . » 

1851, 

1855, 

-1856. . . . . , 

i860 


218.6 

19S.7 

127.2 

91.4 

89.4 

93-4 



Table II. 





year. 


Cost of Repairs of one League of Road. 




By old way of so doing, 
in florins. 


By system of continual 
repairs, in florins. 


-1835. 
1840, 
1845, 
1850, 
-^855, 
i860. 




1,002 
1,086 
1,170 
1,254 

1.339 
1.423 


1,002 
1,086 

975|f 
965f^ 

S35/0 
978ff 



These figures are taken as given by the chief engineer of the 
Baden Public Works, Mr. Keller. He quaintly adds; "These 
tables give clear evidence in favor of the reduced cost by the 
adopted system. That roads are better now than they formerly 
Avere, everybody knows." Another German engineer expresses 
himself to the same effect in a little different way. " It costs no 
tnore," says, he, "to keep the roads in repairs now (1864), than it 
<iid twenty years ago, when this method (of continual repairs) was 
not in use, although labor is now three times and materials are 
twice as dear as they then were." There seems to be no doubt of 
the superiority of the continual repair system in every respect, 
producing very much better roads, and at the same time costing 
less. It need only be tried with us to be thenceforth adopted. 



THE SCIENCE OF ROAD MAKING. 



39 



How TO Repair Roads on the Continuous System. 

We suppose the material for the road covering to lie in regular 
jneasured heaps, all ready to be used, at the storage places, once or 
twice above mentioned, ^s being 200 to 250 feet apart alongside of 
the road, but not encroaching upon it. Then for every two or 
three miles of road, a so-called road-keeper is employed to do the 
necessary work and repairs. An enumeration of his duties will 
comprise at the same time an essay on the art of road repairing. 

1. The road-keeper is to remove the dust formed in dry weather 
by sweeping with a brush broom. This is done to greatest ad- 
vantage just after a slight shower. In muddy weather it is essen- 
tial that the mud be removed by means of brooms or hoes. A 
little mud on the surface causes ruts, and much mud softens up the 
whole road surface. The mud is to be raked up in heaps alongside 
of the road, there left to dry and then carted off. To hinder as 
much as possible the formation of any mud, the surface drainage 
must remain unimpaired; should it be out of order, the water 
standing on the road is to be swept off. To diminish the wear of 
the road in dry times, the road should be sprinkled.* 

2. Inasmuch as the covering gradually wears off, notwithstand- 
ing all precautions, it must be renewed, and should be so renewed 
'gradually, in the same measure as it wears off. The best time to 
[put on new road metalling is during continuous wet weather. 

i 3. In filling up holes, the bottom of the same is to be swept 
iClean of mud, then filled up level with the remainder of the road, 
not in a heap so high above it as to obstruct travel. 
I Every care should be taken to have the new material join as 
speedily as possible with the old portion of the road, and it should 
be so well laid that it will give the least possible hindrance to 
vehicles, which will then not avoid the patched places. 

4. When many ruts occur in a short distance, the deepest only 
are to be filled at first. After the patching in these has become 
solid, then the rest are to be attended to. Long ruts or wheel 



♦Bowles, in his book, "Our New West," mentions the case of the stage road 
Jfrom Sacramento to Virginia City, -via Placerville, one hundred and fifty miles 
'long, and having an annual traffic of seven or eight thousand heavy teams, and 
Iwhose proprietors found that the simplest and cheapest way of keeping it in repair 
Wring dry weather was to sprinkle the whole of it, — one hundred and fifty miles 
|of mountain road. 



40 



THE SCIENCE OF ROAD MAKING. 



tracks are not to be filled up the whole length at once, but only 
short pieces at a time. If this precaution is neglected, -vehicles 
avoid such places, and new ruts are formed elsewhere. 

5. Inasmuch as more material is worn off in a dry season than 
can be put on, there are then, when wet weather comes, large 
places to be repaired. These must be mended by degrees, never 
filling up a piece larger than 8-1 o x 4-7 feet at a time, and not 
having these pieces too near together; when these have become 
solid, then some more may be fitted in and so on till the whole 
is done 

Should it however become absolutely necessary to repair a 
piece of road in dry weather, the place -where the new macadam 
is to be deposited must be loosened up with a pick, then the new 
material put on and a solid top formed by the judicious use of stone 
dust or other binding material and sprinkling with water and. 
pounding down with the shovel, or by what may be called " pud- 
dling" until the whole be solid. Should a frost or very dry 
weather occur immediately after macadam has been put on the 
road in wet weather so that the same will not join on the rest of 
the road surface, the whole must be removed, cleaned and returned 
to the storage heaps for future use. A layer of macadam over the 
whole road should never be put on without treating it immediately 
afterwards in the manner described above for building new roads,, 
that is, mixing in binding material with the top course and rolling 
it in wet weather, or after sprinkling. 

The road-keeper is naturally also the person to see to the 
proper delivery on the part of the contractors, if such there be, of 
the road material in the prescribed places, and to attend to the 
measuring of the same. 

In short and to sum up, it is his business to keep the road in 
good order, and with proper men and surveillance the desired 
result is achieved easily and at a less cost, than by any other sys- 
tem. The quantity of macadam required to keep a certain length 
of road in repair varies very much; it depends, as we have seen,. 
on the care with which the repairs are made, naturally also on the 
kind of stone used and on the amount of travel over road. For a 
width of road = twenty feets the average quantities required per 



THE SCIENCE OF ROAD MAKING. 



4^ 



year to keep a length of ten feet in repair, on the system of con- 
tinuous repairs, has been given as follows : 

Cubic ft. Cubic yds^ 

1. Good material and heavy travel 15-20 = . 55-. 74 

2. Good material and medium amount of travel 10-15 ^ 'ST-'SS 

3. Good material and light travel 5-10 = . 18-. 37 

4. Medium material and heavy travel. 20-25 = .74-. 92 

5. Medium material and medium amount of travel 15-20 = .55-. 74 

6. Medium material and light travel - 10-15 = • 37'-« 55 

7. Third rate material and heavy travel 25-30 = . 92-1 .or 

8. Third rate material and medium amount of travel 20-25 = .74-. 92 

9. Third rate material and light travel 15-20 = .55-. 74 

These are the quantities as given by one authority, but from a 

comparison vs^ith the amounts actually used during a period of ten 

years on thirty-nine roads, having very various amounts of travel 

upon them and being repaired with all kinds of road metal, it 

would seem that the foregoing figures are very ample. 

The exact relation between the quantity of road material that 
is necessary to keep a road in repairs, and the amount of travel over 
it, is still a matter of intelligent observation and discussion. The 
quantity required does not seem to be proportional solely to the 
amount of travel, even with one and the same kind of stone used 
on the same road; as will appear also, when it is considered that 
were there no travel over the road at all, the surfacing would, nev- 
theless, wear out by the action of the frost, the rain, etc. As 
recent an article as the " Annales des P. and C," 1877, p. 226, is de- 
voted to this subject, and does not arrive at any definite general con- 
clusion. 

Repairs of Macadamized and much frequented Streets- 

IN Cities. 

In this case, where the amount of travel in one day is often 
greater than that of a month or more on the town road, the system 
of continuous repairs ceases to be the best available, on accoiint of 
the incessant throng of vehicles not giving any repaired place a 
chance to become solid before it is again ploughed up and scattered. 
Thus in the city of Paris on the Boulevards, etc., the continuous 
system has been abandoned and the practice now is to let the street 
gradually wear down three to four inches, then close half of it 
(divided " fore and aft ") to travel, loosen it all up with picks and 
put on a layer three or four inches (best not to put on more than 
that), spread a thin layer of sand over this, sprinkle and roll heavily. 



^2 THE SCIENCE OF ROAD MAKING. 

It often happens that the men put too much of the sand on; in that 
case, the road, after it is all done, is finally well watered and the 
roller again passed over it a number of times. This operation 
causes the superfluous binding material to come to the surface in 
the shape of thin mud and leaves the road covering as hard and 
smooth as mosaic, making a most excellent driveway. It emits a 
sonorous, ringing sound on being driven over and remains clean 
and without mud throughout the heaviest rain-storms. The rolling 
of the streets in Paris, is done by a company owning a large num- 
ber of steam rollers; in paying them for work done, the city was 
obliged to go back to first principles for a measure of such work, it 
being found impossible to estimate correctly by the square measure 
of surface rolled to such and such a degree of hardness. The meas- 
ure adopted is that of weight multiplied into the distance it has been 
moved, or " feet pounds " as we should say. It has been found 
from many years experience that to roll one cubic meter of maca- 
dam requires 4-5 " Kilometer-tonnes," and this is true whether the 
layer of macadam be three and one-quarter or ten inches thick. 
Expressed in our measures this is 11,020-13,775 feet tons @ 2,000 
ibs.rr: 2.09-2.6 1 mile tons per cubic yard of macadam. 

The advocates of the steam road-roller claim, that by means of 
that machine, they are enabled to make a road that will wear out 
evenly and uniformly for 4 or 5 inches, so that the operation of 
patching need never be resorted to. The steam road-roller can 
also be used for " picking " up a road, for which purpose the roller 
is armed with sharp spikes, and is then driven over the surface to 
be " picked " up. 

Pavements and Trackways. 

No essay on roads would be complete without some mention of 
these two species of road surface, though the use of the former is 
confined principally to streets, and that of the latter is out of date. 

Pavements are either of stone, wood, iron, various concretes, as- 
phalt, and may be of still other substances. 

Stone Pavements. — The modern sizes of paving stones may be 
seen from the following cases. The Boston size is 45^" X 3^" 
X7" deep; New York Belgian, 6-'^' ' y.^-^' ' X6-7' ' deep; new 

\ Broadway pavement, also called Guidet pavement, 3^-4 J^' ' X 10- 
14" X75^-8^ ' ' deep. This last is laid with the long sides of the 



THE SCIENCE OF ROAD MAKING. 43 

stones across the street; and, as far as the author's judgment goes, \ 
is the best size for stone pavement there is. The Boston size is too 
small, and allows of no bond between the separate paving stones. 
Further, the weakest part of each stone being its edge, it follows 
that the more edges there are in a given surface of pavement, the 
speedier will it wear out, each stone becoming rounded and slippery. 
It is only the excellent workmanship and great care displayed in 
setting these stones in Boston that prevents these facts from being 
at once apparent to all. When it is added that in setting pave- 
ments, the natural soil, except it be sand or fine gravel, is in all 
■cases to be excavated 12-19 inches, and then filled up 5-12 inches, 
according to the solidity of the subsoil, with clean, coarse sand or 
fine, clean gravel, and the paving stone set in this and well ram- 
med down with hand rammers, about as much is said on this topic 
as can be said without going into long details. 

From four and one-half to six cubic feet of sand are required 
for every square yard of paving. In setting two different pave- 
ments, the same written rules may be exactly followed in either 
case, yet one be much better than the other, so much depends here 
upon good, careful, conscientious workmanship. 

Wooden Pavements. — There are so many kinds of these, that it 
would be out of place to enumerate and describe them here. Their 
advantages are, less wear on tires and horses, less noise and smooth 
traction; a disadvantage, is their slipperiness in the winter. There 
seems to be a sort of notion that wood pavements and coal tar must 
go hand in hand ; but there certainly is no necessity for this. Coal 
tar is applied as a preservative to the wood; but it must be acknowl- 
edged that many better ones are known and indeed are used, to the 
utter exclusion of coal tar, in all cases where it is desired to pre- 
serve wood, except in this of wood pavements. No wood should 
be used in paving that has not been first subjected to some approv- 
ed method of preservation, or impregnation, as it is frequently 
called. The best manner of setting the same is still a mooted point, 
which it would be presumptuous at present to decide. 

A valuable contribution to the subject of wooden pavements, is 
the report of the Commission appointed by the city of Boston to 
consider this subject, in 1872, City document. No. 100, 1873. The 
Commission come to the conclusion, that the best way to preserve 



44 



THE SCIENCE OF ROAD MAKING. 



the wood that is put down, is by the method called Burnettizing, 
after its inventor, Sir H. Burnett, of England, in 1838. It consists 
of treating the wood to be preserved with chloride of zinc. The 
Commissioners wisely add : " Your Commisioners are of the opin- 
ion that if the city adopts any method of preserving blocks to be 
used for pavements, some additional security should be had that the 
treatment of the wood shall be thorough and complete." As re- 
gards the construction of the pavement, the Commissioners recom- 
mend spruce blocks (for this section of the country), lay stress on 
the necessity of a solid, uniformly constituted, and rolled gravel 
foundation, and then say : " The rows or blocks should be set 
square across the street, and should be about 4 inches thick at top, 
with spaces of about one-half inch between the rows. This may 
be done with blocks of uniform thickness set apart, or with taper- 
ing blocks half an inch thicker at bottom than at top. The latter 
arrangement is the more costly, but it is believed by some that it 
will stand better, by reason of its covering the whole surface of the 
foundation. Longer trial is necessary to settle this point beyond 
dispute. Blocks of only a short chamfer at the top leave the inter- 
space too narrow, as the blocks wear down." The Commission 
named consisted of "two chemists, two practical mechanics, and 
one civil engineer." 

Cast-iron pavements are out of favor on account of their great 
cost, and concrete pavements are a matter of experiment as yet. 

Asphalt pavements are chiefly used in Paris. They are slip- 
pery in wet weather, and produce a very disagreeable, penetrating 
dust in dry weather. It is necessary to prepare a bed of macadam 
to lay them on, and they are not used in Paris except in streets^ 
where the gas pipes are carried either in the sewers or under the 
sidewalks, as any leak of gas would destroy them. Their use is a 
matter of doubtful economy. 

Trackways are, as has been mentioned, out of date. Where a 
common road does not suflice now-a-days, a railroad is built; but 
time was when trackways were of considerable importance. They 
consist, if of stone, of large flat stones, say 12' ' deep and 4-6 feet 
long by i^''-i6'' wide, solidly bedded in two parallel rows, at 
such distance apart as to make of each row a track for the wheels. 
The space between is paved. They are of course very expensive, 
but cost little to repair, and enable a horse to pull a very great 
load. As has been mentioned, Telford made use of such a track- 
way, to avoid cutting down a hill, on his Holyhead road. There 
were two hills, each a mile in length, with an inclination of 5 in a 



THE SCIENCE OF ROAD MAKING. 45 

hundred. It would have cost $100,000 to reduce this grade to 
41/^ in a hundred, but nearly the same advantage, in diminishing 
the tractive force required, was obtained by keeping the 5 in a hun- 
dred grade, with moderate cuttings and embankments, and making 
stone trackways, at a total expense of less than half the former 
amount. 

" Plank roads," once so much in vogue in the United States, 
may not improperly be classed among roads with trackways, and, 
with them, also among the things that were. From their perish- 
able nature, they can never advantageously do more than help the 
development of a new country, and in this, as well as other States, 
are yearly becoming more and more impracticable on account of 
the constantly increasing price of lumber. 

On the Resistance to Motion or the Force Required to 
MOVE Vehicles on Different Kinds of Roads. 

Before, as well as since the introduction of railways, engineers 
in England, Germany and France made many experiments on the 
force necessary to pull different vehicles, at various speeds over 
various surfaces. To enumerate the details of all these experi- 
ments would be perhaps useless; a few general results only are 
here given. 

Experiments, as above indicated, were made by Edgeworth, 
Count Rumford, Bevan, Macneill, Minard, Navier, Perdonnet, 
Poncelet, Flachat, Morin, Kossak, tJmpfenbach, Gerstner, and 
no doubt others, a list of authorities that proves the subject to have 
been well nigh exhausted. The experiments of Morin, made in 
1838-41, appear to have been made with a degree of care and 
accuracy, leaving nothing more to be desired, and the following 
table is an extract from his results,* and gives that fraction of the 
weight of the vehicle and load, which is required to move them on 
k level road: — 

* A full account of Morin's experiments on the resistance to motion of vehi- 
cles, on the wear caused by different vehicles on roads and on the loads different 
vehicles shouM carry so as to produce the same wear, may be found in Morin, 
Experience sur le tirage des Voitures, Paris, 1842. 



46 THE SCIENCE OF ROAD MAKING. 






Character of the Vehicle. 


Character of the Road. 


n 


il 

|5i 




.§ 

If 


Firm soil, covered with gravel 4 '-6''' deep, . 

Firm embankment covered with gravel iX '~ 
ij4" deep, 

Earth embankment in very good condition, . 

Bridge flooring of thick oak plank. 


tV 
tV 


i 


i 


i 

tV 



Broken Stone Road. 

In very good condition, very dry, compact 
and even. ...... 

A little moist or a httle dusty, . • 

Firm, but with ruts and mud, . 

Very bad, ruts 4^-4 J^'' deep, thick mud, . 







walk 


trot 


walk 


A 


A 


tV 


A 


iV 


tV 


^V 


jV 


^T 


tV 


A 


ii 


^T 


tV 


A 


tV 


tV 


tV 


tV 


tV 



1"l 



Good pavement, -j ^ ,* 

( Covered with mud. 



in 






7V 





tV 

A 



To take an example,^suppose we have a truck w^eighing with 
its load 9,000 lbs. How many pounds traction will be required to 
move the same? 

Ans. — On firm soil, gravel 4" -6" deep, that is, a newly re- 
paired road, as we often find it, (|- by table), 1000 lbs.; on best 
kind of embankment, (^V ^7 table,) 310.3 lbs.; on broken stone 
road in good condition, (^ by table,) 166.6 lbs.; on broken stone 
road, deep ruts and mud, {^-^ by table,) 643. lbs. ; on a good pave- 
ment, (J^ by table,) 138.5 lbs. Or, since the tractive force of a 
medium horse when working all day is said to be about 125 lbs., 
we need in the first case, 8 horses; in the second case, 2^ horses; 
in the third case, about i}{ horses; in the fourth case, about 5 
horses; and in the fifth case, only one good horse to move the 
same entire load all day. 

These facts expressed in the preceding page or two in striking, 
yet perhaps dry figures, can be nearly as well given in popular 
language. 

Says a correspondent (Dr. Holland), of the Springfield Repub- 



THE SCIENCE OF ROAD MAKING. ^h 

lican^ writing from England, after describing the kind of horses 
in use there: — 

"Now with all these horses the rule follows that every pound 
of muscle does just as much work on the road as two pounds da 
in America. The cab and omnibus horse does twice as much as 
the same horse does in America. The draft horse does as much at 
the dray as two ordinary dray horses in America, and the little 
horses, which are driven mainly in butchers' carts and grocers' 
carts, will tire a cab horse to follow them with no load at all. 

"In connection with these statements it should be recorded that 
the speed of all vehicles in the streets of London, whether the locali» 
ties be crowded or not, is at least a third faster than it is in corre- 
sponding streets in American cities. The ordinary speed of vehi- 
cles in London, in which passengers or light loads are transported, 
is one which is considered not entirely safe in Main street, Spring- 
field, Mass., and one which, in some streets of Boston or New 
York, would be at once checked by the police. A man who sits 
in a * hansom' finds himself driven at an unprecedented pace 
through crowded thoroughfares, and Yankee though he may be, 
he will often wonder whether he is going to bring up at last with- 
out a broken neck. 

" I mention this matter of speed, particularly, because it shows 
that even more work is done by one horse in London, than by two 
in New York. He not only draws as large a load, but he travels 
with greater rapidity. The streets of London present such a spec- 
tacle of headlong activity as no American city can show, in conse- 
quence of the rapid passage of all sorts of vehicles through the 
streets. I might add to this statement, touching the superior speed 
of the London horses, a word about the greater weight of the 
carriages which they are obliged to draw behind them. All car- 
riages are built more heavily in Great Britain than in America. 
They are built to last, and many of them seem to me to be super- 
fluously heavy. 

" The point which I wish to impress upon my American reader 
is simpl}' this: — that the English horse, employed in the streets of a 
city, or on the roads of the country, does twice as much work as 
the American horse similarly employed in America. This is the 



.48 THE SCIENCE OF ROAD MAKING. 

patent, undeniable fact. No man can fail to see it who has his eyes 
about him. How does he do it? Why does he do it? These are 
most important questions to an American. Is the English horse 
Ijetter than the American? Not at all. Is he overworked? I 
have seen no evidence that he is. I have seen but one lame horse 
in London. The simple explanation is that the Englishman has 
invested in perfect and permanent roads what the American ex- 
pends in perishable horses that require to be fed. We are using 
to-day, in the little town of Springfield, just twice as many horses 
as would be necessary to do its business if the roads all over the 
town were as good as Main street is from Ferry to Central. We 
are supporting hundreds of horses to drag loads through holes that 
ought to be filled, over sand that should be hardened, through mud 
that ought not to be permitted to exist. We have the misery of 
bad roads, and are actually or practically called upon to pay a pre- 
mium for them. It would be demonstrably cheaper to have good 
roads than poor ones. It is so here. A road well built is easily 
kept in repair. A mile of good macadamized road is more easily 
:supported than a poor horse." 

Other results of Morin's experiments are as follows : 
I. The force required to draw a vehicle, is directly proportional 
\o the load, and inversely so to the diameter of the wheels ; in other 
more common words, the tractive force increases in the same ratio 
that the load increases, and the diameters of the wheels decrease. 

. 2. On a paved or well built macadam road, the tractive force 
is independent of the width of the tires, provided the same is more 
than three or four inches. On compressible roads, such as new 
gravel, on a meadow, etc., the tractive force diminishes with an 
increase in the width of the tires. 

3. Other circumstances being equal, the tractive force is the 
same for vehicles with and without springs as long as the horses 
are not moving faster than a walk. 

4. On paved and well macadamized roads the tractive force 
increases with the velocity, according to the law, that beyond a 
velocity of 21^ miles per hour (3.3 feet per second) the increase of 
the tractive force is in direct proportion to the increase in velocity 5 



THE SCIENCE OF ROAD MAKING. 



49 



ChiS increment is however less, the softer the track or road and 
According as the vehicle is best provided with springs. 

5. On soft earth embankments, or on sand or sods, or on streets 
newly covered with gravel, the tractive force is independent of the 
velocity. 

6. On a well-made pavement of regular shaped stone, the trac- 
tive force, horses on a walk, is about three-fourths of that on a 
good macadam road, but with horses on a trot, the two are about 
equal. 

7. The wear on the road is greater the smaller the diameter of 
the wheels and greater in the case of vehicles without, than for 
those with springs. Most road-rollers, as now in use, have two 
small a diameter besides being two light and consequently do not 
properly compress the road surface. 

8 The tractive force, as well as the wear on the road, is greater 
in the case of vehicles that have their wheels placed at an angle 
with the vertical by reason of the ends of the axle-trees being bent 
down, than for those that have their wheels set plumb and the cen- 
tre line of the axle-trees level* 



50 



THE SCIENCE OF ROAD MAKING, 



PAET II. 

ON THE "BEST METHODS OF SUPERINTENDING THE CON^ 
STRUCTION AND REPAIR OF PUBLIC ROADS IN THIS COM- 
MONWEALTH " (MASSACHUSETTS). 

In looking for a solution of this question the people of the 
Commonwealth man turn as they choose, either to the West or to 
the East, to see a guiding star; to the city of Chicago, or to the 
city of London, both under a republican form of government, alike 
or similar to that we live under. It lies in the establishment of a 
Board of Works, composed of a number of able men, well paid for 
their services, gradually changing in their membership in the 
Board who shall have this and only this as their occupation, and 
who can therefore be held responsible for their acts. This is the 
system that has been adopted both in London and in Chicago and 
with remarkable success and resultant benefits. There are many 
other systems in use in foreign countries all of which however 
seem to be inapplicable here, placed as we are, under so different 
forms of government; hence, though well acquainted with the sys- 
tems adopted in France and in Germany, the writer has not de- 
scribed them here. 

The history of " the Metropolitan Board of Public Works of 
the City of London" is about as follows: 

What is known as the city of London consists in reality of a 
great number of what we should call towns, there called parishes, 
and of which the " City of London " is only one single member. 
Each one of these parishes had, and still has in most respects, its 
own local government, and in consequence took care of its drain- 
age, its streets, etc., etc., as seemed best and as it liked, some bet- 
ter, some worse, and some not at all. This state of things in the 
matter of drains and sewers finally led to a most deplorable condi- 
tion of affairs; there was not nor could there under these conditions 
be such a thing as a system of sewers, and consequently a proper 
and adequate drainage; the death-rate increased to an alarming ex- 
tent and matters came to be universally regarded as past all endur- 



THE SCIENCE OF ROAD MAKING. ^y 

iince. What could be the remedy? No well grounded complaint 
could be made against the majority of the men composing the vari-- 
ous local governments, since they were good and honest citizens^ 
and hence no change in the separate goverements could ever bring; 
relief. The fault lay not in the men, but in the system of ruling; 
they were called upon to fulfill, that is, in the incompetent and 
faulty treadmill of government they were annually called upon to 
keep in its usual operation. It was then seen that by having aix 
elected power to supervise and regulate the sewage affairs of the: 
whole metropolis, a complete system of drainage could be carried 
out, and thus only. Such a regulating power is exercised by the 
metropolitan Board of Public Works, chartered by Act of Parlia- 
ment and composed of members elected from all» parts of London.. 
It is perhaps in place here to explain what is ineant by a system of 
sewers as the same definition will hold good in other matters; as 
for a system of roads, of drainage and irrigation of lands, etc. 
Perhaps the best illustration would be to refer one to the veins and 
arteries in the human body, or to the body of a tree, from its trunk 
through the branches growing smaller and smaller down to the 
smallest twig that may be on it. It will be at once seen how dif- 
ferent any arrangement, in which may be the wisdom to contrive^ 
the strength to uphold and the beauty to adorn, like this, is from a 
miserable patchwork such as cannot but arise where the separate 
parts of one whole are each left to guide themselves without any 
unity of action or design, as to their final resultant. The London. 
Board of Public Works had some extraordinary powers conferred 
upon it, such as the right to levy assessments on real estate bene- 
fitted by their improvements, and others. Originally constituted 
merely to plan and execute a system of sewerage for the metropo- 
lis, this Board of Public Works soon showed itself so useful and 
beneficial in its actions that other matters were placed in its charge, 
such as the laying out of new streets, the building of the Thames 
embankment, — a work of exceeding great magnitude and import- 
ance, — and there seems to be no doubt that in all public works 
London will find it advantageous to employ its Metropolitan Board 
of Public Works. 

In the city of Chicago there has been a Board of Public Works 



52 THE SCIENCE OF ROAD MAKING. 

almost from the very start. It arose there from the union of the 
water supply and the sewerage commissioners, and has existed 
since May, 1861. No less than in London, it has proved to be of 
great benefit to the community ; and it would have been impossible, 
under any other system, to have executed in so satisfactory a man- 
ner the many and useful public works for which Chicago is famed. 
At the risk of introducing in this place some very dry reading, a 
general synopsis of those parts of the city charter which relate to 
the Chicago Board of Public Works is here given. The whole 
may be found in a copy of " Laws and Ordinances, Chicago, 1866:" 

Sec. I. Establishes a body known as the " Chicago Board of 
Public Works," to consist of (3) three members, chosen by the 
people, one from ^ach division of the city. 

The first three chosen for one, two and three years; after that, 
one each year for three years. 

Sec. 2. Each member of board shall receive annual salary of 
three thousand dollars (by Act of February, 1866); give bonds for 
faithful discharge of duties; pay over all moneys, papers, etc., at 
expiration of his term, or when ordered by city council. 

Sec. 3. Board to elect president and treasurer, and make by- 
laws. 

Sec. 4. Majority constitutes quorum ; records to be kept of pro- 
ceedings; copies of all plans, estimates, etc., to be kept; report 
(annual) to be rendered on or before each year, 

or when required by city council. Each member authorized to 
administer legal oaths. 

Sec. 5. Board shall have special charge and superintendence^ 
subject to the laws and ordinances of the city council, of all streets, 
lanes, alleys, etc., in the city of Chicago, and of all walks and 
crossings in the same, and of all bridges, docks, wharves, public 
places, landings, grounds and parks in said city, and of all halls, 
engine-houses, and other public buildings in the city belonging 
to city, except school-houses, and of the erection of all public 
buildings ; of lamps and lights in streets, etc., and in public build- 
ings, and repairs of same ; of the harbor works and improvements ; 
of the city sewers and drains and of the water works; of the fire- 
alarm telegraph, and all public works and improvements hereafter 



THE SCIENCE OF ROAD MAKING. ^3 

to be commenced by the city, as well as such other duties as may 
be prescribed b}- the city council by ordinance. 

Sec. 6. All applications or propositions for improvements or new 
works of kind specified in section five, shall hereafter be first made 
to Board of Public Works, or if made first to city council, shall be 
by them referred to Board. Upon receiving application, Board 
shall investigate the same, and if they find such work necessary 
and proper, shall thus report to city council, with an estimate of 
the expense thereof. If they do not approve of such application, 
they shall report the reasons for their disapproval, and the city 
council may then in either case, reject said application or order the 
doing of work or making of public improvement, after having 
first obtained plans and estimates thereof. The Board may also in 
like manner recommend whenever they think proper, any improve- 
ment of the nature above specified, though no application has been 
made therefor. 

Sec. 7. Shall be duty of Board to procure for city full plans 
and estimates of contemplated improvements, when so ordered by 
council. 

Sec. 8. Whenever any public improvement shall be ordered by 
city council, and money appropriated. Board shall advertise for pro- 
posals for doing work; plans and specifications of same first 
placed on file in office of Board, which plans and specifications 
shall be open to public inspection; advertisement to state work to 
be done, and to be published ten days at least. The bids shall be 
sealed bids., directed to bofrd, and accompanied by bond to city, 
signed by bidder and two responsible sureties, in sum of two hun- 
dred dollars, conditioned he shall do work if awarded to him; in 
case of his default to do so, etc. Bids to be opened at time and 
place mentioned in advertisement. 

Sec. 9. All contracts shall be awarded to lowest reliable bidder, 
and who sufficiently guarantees to do work under superintendence 
and to satisfaction of Board: provided^ that the contract price 
does not exceed the estimate, or such other sum as shall be satisfac- 
tory to Board. Copies of contracts to be filed with city comp- 
troller. 

Sec. 10. Board reserves right, in contracts, to decide questions 



54 



THE SCIENCE OF ROAD MAKING 



as to proper performance of work and meaning of contracts; in 
case of improper construction may suspend Avork and relet same, 
or order entire reconstruction; or may relet to other contractors 
and settle for work done, etc. 

In cases where contractor properly does work, Board may, in 
their discretion, as work progresses, grant to said contractor esti- 
mate of amount already earned, reserving fifteen per cent, there- 
from, which shall entitle holder to receive amount, all other con- 
•ditions being satisfied. 

Sec. II. In case prosecution of any public work be suspended, 
or bid be deemed excessive, or bidders be not responsible, Board 
may, with written approval of treasurer, where urgency of case 
and interests of city require it, employ workmen to perform or 
complete any improvement ordered by council : provided^ that the 
cost and expense shall in no case exceed the amount appropriated 
for the same. 

Sec. 12. All supplies of materials etc., when costing over five 
hundred dollars, to be purchased by contract, subject to same con- 
ditions as letting out work. 

Sec. 13. Whenever Board think necessary for interests of city, 
to protect same from damage or loss, shall report thus to aldermen, 
and reasons for same, asking power to give contracts without 
notice required above, and aldermen may grant request: provided^ 
three-fourths vote for it. 

Sec. 14. Whenever Board is of opinion work may be better 
■done without contract, shall so report to council, and same may 
authorize Board to procure machinery, materials, etc., hire work- 
3iien, etc.: provided^ a three-fourths vote be in favor of granting 
authority. 

Sec. 15. All contracts and bonds by Board to be in name of 
city. 

Sec. 16. No member to be interested in any contract; all con- 
tracts made with any member interested, city may declare void; 
.any member so interested shall forfeit his office and be removed 
therefrom; the duty of every member of Board and of every 
ofl^icer of city to report delinquency, if discovered. 

Sec. 17. All existing contracts executed by city, by water or 
sewerage department, etc., to be carried out by Board. 



THE SCIENCE OF ROAD MAKING. 



55 



Sec. iS. Board shall nominate each year the various officers, 
now provided for by ordinance, which serve in the departments 
tinder their special charge, the city engineer, superintendent sew- 
ers, streets, etc. Shall be empowered to employ from time to time 
such other superintendents, clerks, etc., as they may deem neces- 
sary, subject to ordinance as regards pay, etc. 

Sec. 19. Board to have charge and superintendence of works 
made lor city, and paid for by private individuals or by State. 
Plans for same to be approved by Board. 

Sec. 20. Board shall, on or before every year, 

submit to auditor, by him to be presented to council with annual 
estimate, statement of the repairs and improvements necessary to 
be undertaken for current year, and of the sums required by Board 
therefor; report to be in detail; report, having been revised by 
council, sums required shall be provided for in annual tax levy. 
All moneys to be paid to any person out of moneys so raised, shall 
be certified by president of Board to auditor, who shall draw war- 
rant on treasurer therefor, stating to whom payable and to what 
fund chargeable; such warrant to be countersigned by president ot 
Board. 

Sec. 21. Board to keep accounts showing moneys received 
and spent, clearly and distinctly, and for what purpose. Accounts 
to be always open for inspection of auditor or any committee ap- 
pointed by city council. 

The object of introducing this synopsis here has been to give 
a complete picture of just what such a BoArd of Public Works is. 
It will be seen upon a little examination how entirely different a 
thing it is from the usual and only too customary "committee." 
Perhaps the greatest fault of a committee is its entire lack of what 
•might be called body and soul. If corporations, as has been said, 
have no souls, a committee may be said to have neither body nor 
soul. It is alive to-day, wields great power, decides vital and im- 
portant questions, and yet is nowhere to-morrow, and seemingly 
even its component atoms have vanished fjom the face of the 
earth. It is amusing and yet sad, when the action of some such 
committee has caused trouble to read some time after, that it all 
'" is exceedingly discreditable to whoever is responsible for it." 



56 THE SCIENCE OF ROAD MAKING, 

How much better to have a conservative, expert and reliable body, 
the members of v^^hich have no other business than to attend to 
their duties as such, who are well paid for it and consequently can 
at any time be held strictly responsible for their actions. With 
such a power, wisely governing and regulating the roads of this 
Commonwealth, it would be an easy matter to make thorough im- 
provements in the legislation concerning roads and in the roads, 
themselves. 

These are two changes the need of which is generally felt at 
present and has found expression in various ways. 

It may be well to quote one at least, notable for saying very 
much in little compass,— of these calls for improvement, in this 
connection, and adding some more as belonging to this subject in 
the form of an interesting appendix. Says Gov. Claflin in his In- 
augural: "Few things are of greater importance to a community, 
or a surer test of civilization, than good roads. Those of our citi- 
zens who have visited Europe are unanimous in the opinion that 
our public roads are far inferior to those of other countries, where 
the means of easy and safe communication are better appreciated. 
The science of road-making is apparently not well understood; or,, 
if it is, the present modes of superintending the construction and 
repair of roads are so defective that the public suffers to an extent 
of which few of us are aware. It may be found upon investigating 
the cause of our miserably poor and ill-constructed roads, that the 
laws relating to this subject need revision, so as to give more uni- 
formity in their construction and the repair of our highways. It 
is evident, also, that the science of road-making should have a 
prominent place in the course of applied mathematics at the Massa- 
chusetts Agricultural College." 

We stand then in this matter of roads at precisely the same 
point that the good people of London did ten or a dozen years 
ago in the matter of their drainage, and our reinedy is the same*. 
The fault lies in the machinery of government; originally built 
up to cater to the wants and needs of a newly settled country, — 
a colony breaking a path through the wilderness, — it has long 
since ceased to satisfy the demands of the present State in no mat- 
ter so essentially as in that of its government and laws relating to 



THE SCIENCE OF ROAD MAKING. 



57 



common roads and highways. This is a subject requiring special 
knowledge, to be acquired only by long experience or the shorter 
rrethod of imbibing the experience of others, which, on analyzing 
It, is all that any study amounts to; formerly it was not so, and 
most any one sufficed to make improvements on Indian paths. 
We need then an expert government on this point. 

There should be a distinction made between first, second and ' 
third class, or between, as they might be called. State, County and 
Town roads; the first two should not be left to be dealt with as it 
is the pleasure of each town. A chain cannot be perfect unless 
every link in it is so; no more can a road. The State must attend 
to the State and County roads and set a proper example at least to> 
be followed by the towns in the case of their roads. We need then 
a higher power than that of the towns. 

It has been previously shown how we need a power that can 
be held responsible and is somewhat permanent, and to put it all 
together, we need, to order and maintain our highways, a Massa- 
chusetts Board of Public Works. For some years it would have 
its hands full in improving the existing main roads and laying out 
some new ones, but in course of time, as in the older countries of 
Europe, its principal business would be the maintenance of the 
roads. It must be remembered that the Board of Public Works 
is merely the intelligent servant and adviser of the legislative and 
executive; whatever sums the legislature appropriates for certain 
objects, that is taken by the Board and made to yield its most in 
the shape of work accomplished. Beyond this and keeping its 
accounts, it has nothing to do with money or taxation. 

The small state of B^den, a part of Germany, has been hereto- 
fore mentioned as a mode] in road construction and the care of the 
same. From a brief history of the roads of that country and their 
present management, we may take some useful notes. The account 
is that of the Chief Engineer of the department of "Roads and 
Hydraulic Engineering," which has this matter in charge and is 
therefore reliable. 

" In Baden the condition of the roads has been a subject of 
great care. Within the last forty-five years many millions have 
been spent upon them, and experience has shown this expenditure 



58 



THE SCIENCE OF ROAD MAKING. 



to be one of those most advantageously spent. As most of the 
roads are well laid out, and as there are plenty of them, there 
remains now (1863) mainly the keeping in repair of the roads to 
be attended to and not to build any new ones. Our endeavor now 
is, to do this at the minimum of cost. Statistics gathered on this 
subject, show good results and point out to us the means of arriv- 
ing at still better ones. The present road law was made in 18 10. 
That part of the old law which relates to the maintenance of roads 
is still in force, but that part requiring labor as a road-tax was 
abolished in 1831, and likewise most of the road police regulations. 
The appropriation for roads had to be increased 250,000 florins to 
pay for the abolished road-tax labor and to make up 170,000 florins 
previously received from tolls, which were also abolished in 1831. 
The system now is as follows : All town roads are taken care of by 
the towns. The State merely appoints and pays a road-master, so 
called, who superintends fifteen or twenty road-keepers and reports 
on the state of the roads, the reasons for their bad condition, if that 
be the case, what is needed, etc. The law for second class or 
county roads was formerly, that when they were of importance to 
several towns, they had all to help maintain the same. As this 
gave rise to continual bickering and quarreling, in which the road 
suffered most, it was changed in 1856. They are now taken care 
of under the direction of the State and paid for partly by the State 
and partly by the towns in which they are situated. Most of the 
roads under this head are those which have risen in importance 
since the building of railroads, and are generally those that lie per- 
pendicular to the direction of the railroad they are influenced by. 
The towns not having the means very often to properly improve 
and repair such, it was found necessary and expedient to give them 
the aid of the State, and in order to procure the necessary funds, 
all roads that run parallel to railroads and all those that had lost 
their importance by the construction of railroads, were in 1855 
stricken from the list of state roads. These latter as the name im- 
plies, are wholly under the care and kept up at the expense of the 
State. 

In 1835, the total length of the State roads was , . 1,430.8 English milet 
la 1855, " " " " . . 1,500.8 



THE SCIENCE OF ROAD MAKING. 



59 



Country. 


Year. 


Baden. 


1871. 


Prussia. 


187I. 


France. 


1872. 


Hanover. 


1871. 


Massachusetts. 


1875. 



In 1855, by excluding several State roads, this last length English Miles. 

was reduced to . 1,142.4 '• 

In 1861, it had increased to 1,190.0 " 

Second class Roads {heeping fartly faid for by State.') 

In 1835, the length of these was 467.6 English miles. 

In 1861, " •• 630.0 " 

So that the State had, in 1 861, in all, 1,820 English miles of 

road to maintain, the towns helping to pay on six hundred and 

thirty miles thereof. 

The areas, population, and population per square mile of Baden, 
Prussia, France, Hanover and Massachusetts, according to recent 
census, are as follows: 

Area, sq. miles. Population. Pop. per sq. mile. 

5,?9I. 1,461562. 243. 

134,045. 24.643,698. 184. 

204,088. 36,102,921. 177, 

14,857. 1,963,080. 132. 

7,800. 1,651,912. 212. 

Baden did have, at a time when her population per square mile 
was less than it is now, and Prussia, France, Hanover, and many 
other countries that could be named, have now got, and for the past 
^^o or 50 years have had, a system of common road management 
and resultant common roads, of the character above described; 
while Massachusetts with a population of 212. per square mile, and 
corresponding wealth, and others of the States of the Union, have 
a species of highway management, and its resultant and corres- 
ponding sort of highways, which, in thinking of the roads of the 
countries named, are but as evidences of a partial civilization. 

" The statistics of the road repairs are kept in the following 
manner. The road-keepers are required to keep a record of all 
draught animals that pass in either direction. Horses that are 
being ridden, animals not before a vehicle, and teams going to and 
from the fields, are not counted. These records are kept only dur- 
ing the working hours. Likewise, not during the whole year, but 
only four months in each year, so selected as to give an average 
amount of travel. The travel on the road on Sundays and out of 
working hours is taken from a few observations; it is a very small 
percentage of the whole. At the end of the year these records 
and observations are collected and graphically represented on a 
map of the whole State. The different roads are drawn of a dif- 
ferent thickness of line, according as the amount of travel on them 
is greater or less. The quantity of road metal used per yard of 



6o _ THE SCIENCE OF ROAD MAKING. 

road, and the kind of metal used, give the data for another such, 
map, in which the different colors of the roads represent the differ- 
ent materials used in their repair, and the figures on them and their 
thickness show the number of cubic yards per mile required to 
keep the road in order. Finally, we have a third map, which indi- 
cates, by the thickness of the several lines representing the roads 
and by the figures on them, the total cost per mile of repairing the 
road one year." 

With this picture of a country happy and prosperous, in the 
possession of good and well-kept roads, it may be well to leave the 
subject. 

Massachusetts wants for her proper development, much better 
roads than she now has; and, reckoning for a period of say fifty 
years, she can have these good roads, and have them kept in order, 
at a less cost than that of keeping up the present poor ones for the 
same time. Besides this, we should see in the one ease a healthy 
state of internal convnunications and trade; in the other an absence 
of both. Let each citizen so act and do his part, that these benefits. 
may accrue to the Commonwealth. 



THE SCIENCE OF ROAD MAKING. 6 1 



APPENDIX. 



For the sake of arriving at some practical end, I have requested 
the gentlemen to whom the prizes for essays were awarded to sug- 
gest what form of legislation would be desirable as a change from 
our present inefficient system of road management, to one which 
should promise better, more economical and more satisfactory re- 
sults. The large and varied experience and observation of these 
gentlemen, all of whom are competent engineers, entitle their 
opinions and judgment to favorable consideration ; and the follow- 
ing, submitted by them, may serve as a basis or outline for future 
legislation. C. L. F. 

AN ACT FOR THE MORE PERFECT CONSTRUCTION AND MAIN- 
TENANCE OF THE Common Roads or Highways through- 
out THIS Commonwealth (Massachusetts). 
Sec. I. Establishes a body to be known as the State Board of 
Highways and Bridges, to consist of three skillful civil engineers, 
or persons practically expert in the science of road-making, to be 
appointed by the Governor with the advice and consent of the 
Council, and to have their office in the State House. 

Sec. 2. It shall be the duty of the Attorney- General, person- 
ally or by his deputy, to give his council and opinion on such mat- 
ters as he may be called upon by the Board, for which service his 
■compensation shall be 

Sec. 3. The first appointment of members of the Board of 
Highways and Bridges shall be made on or before , 

and there shall be appointed one member each for the terms of 
one, two, and three years; after that there shall on or before 
each year be appointed one member for the term of three years. 

Sec. 4. Each member of the Board shall receive an annual 
salary of dollars; give bonds for the faithful discharge 

of his duties; pay over all moneys, papers, etc., at the expiration of 
his term or when ordered by the Governor and Council. 

Sec. 5. Board are to elect a president and treasurer, and make 
their own by-laws. 

Sec. 6. A majority of the Board constitutes a quorum; records 
to be kept of all the proceedings; copies of all plans, estimates, etc., 



62 THE SCIENCE OF ROAD MAKING. 

to be kept; report to be rendered on or before each 

year, or when required by the Governor and Council. Each mem- 
ber authorized to administer legal oaths. 

Sec. 7. Said Board shall prepare and submit to the 
legislature a plan for the systematic classification of all the highways 
and townways in this Commonwealth into two or more of the fol- 
lowing three classes: — 

Class I. State roads, to be controlled and maintained wholly by 
the State. 

Class 2. District roads, to be controlled and maintained by the 
State, but the expense thereof to be borne by the towns and cities 
of the districts in which said road shall lie, and the State, in such 
proportions as said Board shall apportion. 

Class 3. Town roads to be controlled and maintained as now 
provided by law. 

The construction of new roads, of the three classes above speci- 
fied, to be done as follows: — 

Class I. State roads, to be laid out and built by the State, 
through the Board of Highways and Bridges. 

Class 2. District roads, to be laid out, etc., by the county com- 
missioners, as now provided, but the board to have the final ap- 
proval or disapproval of the proposed plans and profiles for said 
road, and also to have the charge and superintendence of their con- 
struction. 

Parties aggrieved by the refusal or neglect of county commis- 
sioners to lay out a road, to have the right to appeal to the Board 
of Highways. 

Class 3. Town roads, to be laid out and constructed as now 
provided by law. 

Sec. 8. The paying of road taxes by labor is hereby abolished, 
and all road taxes are hereafter to be paid in cash. 

Sec. 9. Board shall have the special charge and superintend- 
ence, subject to the laws and resolves of this Commonwealth, of 
all the highways and bridges, and the public works appertaining 
thereto, which are or shall be executed or maintained, wholly or in 
part by this Commonwealth. They shall also perform such other 
duties as may be required of them by the general court or the Gov- 
ernor and Council. 

Sec. 10. Whenever any highway or bridge, or public work ap- 
pertaining to these two, shall come partly within the province of 
this Board, and partly within that of any other State board, already 
constituted, then such subject shall be discussed and decided upon 
in a joint convention or conventions, composed of equal numbers 
of this and the said other State board, and some member by them 
chosen as presiding officer. 

Sec. II. All applications or propositions for improvements 01 
new works, of the kind specified in section nine as coming within 
the province of this Board of Highways and Bridges, and intended 
to be laid before the legislature, shall hereafter be first made to this 



THE SCIENCE OF ROAD MAKING. 



63 



Board. Upon receiving such application, Board shall investigate 
same, and if they find such v^ork necessary and proper, shall thus 
report to the legislature, w^ith an estimate of the expense thereof; 
if they do not approve of such application, they shall report the 
reasons for their disapproval. 

The Board may also, in like manner, recommend, whenever 
they think proper, any improvements of the kind above specified, 
though no application has been made therefor. 

Sec. 12. It shall be the duty of the Board to procure for the 
legislature full plans and estimates of contemplated v^orks or im- 
provements w^hen so ordered by the legislature. 

Sec. 13. Whenever any w^ork shall have been authorized or 
ordered by the general court and the money appropriated therefor, 
Board shall advertise for proposals for doing said work; plans and 
specifications of the same first to be placed on file in office of Board, 
which plans and specifications shall be open to public inspection; 
advertisement to state work to be done and to be published ten (10) 
days at least. The bids shall be sealed bids, directed to Board and 
accompanied by bond to the Commonwealth signed by bidder and 
two responsible sureties, in sum of two hundred ($200) dollars, 
conditioned he shall do the work if awarded to him, in case of his 
default to do so, forfeits, &c. Bids to be opened at time and place 
mentioned in advertisement. 

Sec. 14. All contracts shall be awarded to the lowest responsi- 
ble bidder and who sufficiently guarantees to do work under super- 
intendence and to satisfaction of Board; provided that the contract 
price does not exceed the estimate or such other sum as shall be 
satisfactory to Board. Copies of contracts to be filed with state 
auditor. 

Sec. 15. Board reserves right in contracts to decide questions as 
to proper performance of work and meaning of contracts; in case 
of improper construction may suspend work and relet the same; or 
order entire, re-construction; or may relet to other contractors and 
settle for work done, &c. In cases where contractor properly does 
work, 'Board may in their discretion as work progresses, grant to 
said contractors estimates of amount already earned, reserving 
fifteen per cent, therefrom, which shall entitle holder to receive 
amount, all other conditions being satisfied. 

Sec. 16. In case prosecution of any public work be suspended, 
or bid be deemed excessive, or bidders be not responsible. Board 
may, with written approval of governor, where the urgency of the 
case, or interests of the Commonwealth require it, employ work- 
men to perform or complete any work ordered by the legislature : 
provided, that the cost and expense shall in no case exceed the 
amount appropriated for the same. 

Sec. 17. All supplies of materials, &c., when costing over five 
hundred ($500) dollars, to be purchased by contract, subject to same 
conditions as letting out work. 



64 



THE SCIENCE OF ROAD MAKING. 



Sec. 1 8. Whenever Board think necessary, for interests of the 
Commonwealth, to protect same from damage or loss, shall report 
thus to governor and council and reasons for same, asking power 
to give contracts without notice required above, and governor and 
council may grant request, provided three-fourths vote for it. 

Sec. 19. Whenever Board is of opinion a work may be done 
tetter without a contract, shall so report to legislature, and they 
shall procure machinery, materials, &c., hire workmen, &c., to do 
said work, whenever so authorized by the legislature. 

Sec. 20. All contracts and bonds by Board to be in the name of 
the Commonwealth. 

Sec. 21. No member of the Board to be interested in any con- 
tract; all contracts made with any member interested, governor 
may declare void, and shall remove such member so interested from 
office. It is the duty of every member of the Board and every 
officer of the Commonwealth to report any such delinquency, if 
discovered. 

Sec. 22. Board shall be empowered to employ such engineers, 
clerks or other assistants, as shall be provided for by the legislature. 

Sec. 23. Board shall, on or before every year, submit 

to the auditor, by him to be presented to the legislature with his 
annual estimate, a statement of the repairs and new work needed 
for the current year, and of the sums required by the Board there- 
for; report to be in detail; all sums appropriated therefor to be in- 
cluded in the annual tax-levy. 

Sec. 24. All moneys to be paid to any person out of moneys so 
raised, shall be certified by president of Board to auditor, who shall 
draw warrant on treasurer therefor, stating to whom payable and 
to what fund chargeable; such warrant to be countersigned by 
president ot Board. 

Sec. 25. Board to keep accounts, showing moneys received and 
spent, clearly and distinctly, and for what purpose. Accounts to be 
always open for inspection of auditor or any committee appointed 
by the legislature. 



THE CONSTRUCTION AND MAINTENANCE OF 
ROADS.* 



The writer wishes to give the Society some statistics and suggestions 
regarding the construction and maintenance of wheelways, partly drawn 
from his experience in charge of such work and from observation and 
information acquired in this country, and recently in London and Paris. 

Earth Roads. 

In the construction of an earth or gravel road the effort should be to 
keep the material near the surface as nearly homogeneous as possible, 
that the surface may be uniformly hard. The upper layers at least should 
be thoroughly rolled in thin layers, with sprinkling, if the material is too dry 
to pack well. The most efficacious roUei for this purpose is of two sets of 
disks, one about eight inches less in diameter than the other, placed alter- 
nately on the axis of the roller. It is understood that the cost of com- 
pactmg reservoir embankments with this roller is about three-fourths of a 
cent per cubic yard. The writer has never seen it used in road mainte- 
nance. 

When the soil is sandy but little can be done besides covering it with 
some more tenacious material. Clay, or clay hard-pan, is the best, unless 
a sufficient coat of gravel can be afforded. Even a clay road, if the traffic 
is not too heavy, can be kept in a firm state by careful and continuous 
maintenance ; a coat of sand or hard-pan is, of course, desirable. 

The plan often pursued of repairing roads once or twice a year is not 
economical, for the dilapidations increase in a heavy ratio after they com- 
mence. 

A fair average for re-forming a mile of old road 30 feet wide between 
gutters, where the material was mostly cast from the sides, was 164 days, 
10 hours each, of laborers, and two days of a double team hauling earth, 
carrying away stones, and moving tool-box. The use of a railroad scraper 
would have been an economy. 

Maintenance is most economically performed by double teams, with 
hones or scrapers, rollers, and the watering-cart in dry weather. The 
hone or scraper is often an oak plank, 2 inches thick, 10 inches broad, and 

*By Edward P. North, C. E., Moniber of the Society, read before the American Society of Civil 
En^neers, April 16th. 1S79. 



66 CONSTRUCTION AND MAINTENANCE OF ROADS. 

9 or lo feet long, shod on its lower edge with a )i-vciz\i plate of iron, 
Drawn vertically along the road either by a tongue or a chain — in the first 
case it has two handles like plow handles — in the second it has a vertical 
handle, and the earth is dumped by pushing it forward ; a piece of plank 
about 3 feet long being fastened behind, by riding on which the driver can 
regulate the amount of earth moved. These are drawn over the road, in- 
clined 7 or lo degrees from a perpendicular, to the line of travel. So that, 
besides filling small depressions, they, to a slight extent, scrape the earth 
to or from the centre of the road. There are also some patented machines, 
combining a scraper and roller in a frame, which are said to be very effec- 
tive. 46,000 to 47,000 square yards can be covered in a day, while not 
more than 2,300 can be put in order if the road is rutted and gullied. 
While hones are of little use on muddy roads, they are effective just as it 
is drying. 

The ordinary type of roller has 6 rings, the whole length being 6 feet, 
and weighing about 2 tons, with frames that will hold lyi tons of stone. 
A better is of 2 rings, 3 feet long, also weighing 2 tons. Another is figured 
in Clemens Herschel's Prize Essay on Roads, and in General Giimore's 
Roads, Streets and Pavements. 

The roller should follow the re-forming of the roadbed, whether with 
hones, shovels, or the ordinary railroad scraper. 

The writer has rolled earth roads with a 15-ton steam roller, but not 
enough to be certain as to its economic value ; where the soil contained a 
fair amount of clay, the roadbed was left very hard, and w^ore well. 

A water cart holding 60 cubic feet will water 830 to 860 square yards, 
and can be drawn by an ordinary team over any road that is worth 
watering. Tvvo sprinklings per day will keep the road in good condition, 
though not free from dust in hot weather or high winds, if there is much 
traffic on the road. Sprinkling is the only thing that will keep a road 
from breaking up in long continued dry weather. 

The treatment of gravel roads compacted either by traffic or horse 
rollers, differs very little from that pursued with earth roads. When the 
gravel is over i inch in diameter, it is almost impossible to keep the road- 
bed from breaking up when dry, and ^ inch would be a better size, unless 
continuous watering can be depended on in dry weather. Small gravel 
(and the same remark applies to metal for Macadam) makes a pleasanter 
road for travel, and can be more easily kept in order. 

St. Nicholas Avenue, which will be mentioned further on, was m.ade 
from nearly clean Roa Hook gravel, by the aid of a 1 5-ton roller, but 
with a horse roller it will be necessary to add clay, loam or some softer 
material, to any hard or clean gravel to act as binding. W. H. Grant, 
Member of the Society, in his valuable description of the roads of Cen- 
tral Park, says of Roa Hook gravel, " it being more than ordinarily 



CONSTRUCTION AND MAINTENANCE OF KOADS. 67 

clean and hard, bears an intermixture or adulteraticn of 20 to 25 per cent 
of inferior material to perfect its binding properties." These roads 
have a foundation of rubble stone, not so firmly packed as Telford 
specified, covered with quarry chips and hard-pan, which was rolled 
with 2-horse rollers, 6 feet long. " This is thoroughly done to prevent 
the gravel filling the cavities of the rubble bottom, so that its cellular 
character may remain unimpaired to facilitate drainage." The gravel 
was applied to two or three successive layers, making a depth of 4 to 6 
inches. Each layer was rolled with a 2-horse roller, and the last w Ith one 
weighing 6%, tons, 5 feet long, giving 217 lbs. per inch pressure. These 
roads, which were thoroughly underdrained and side guttered, have long 
been famous for their excellence ; they are pleasanter for light travel than 
Macadam, and are easily kept in repair, except in wet weather, when they 
become muddy, and when neglected, the larger pebbles make a rough 
road for buggy riding. 

For horse rolling binding should be applied as sparingly as possible, 
and on the last layer, after it has been compacted, simply as a glaze to 
hold the stone ; if it contains clay, it should be as moist as possible, not 
to stick to the roller. 

The so-called Tompkins Cove gravel, which is much used for en- 
trance drives to gentlemen's places about New York, is a broken lime- 
stone, apparently of the cement series. It is usually spread over the 
road, and compacted by the wheels. The darker colored stone is very 
pleasant to the eye, and it readily makes a smooth wheelway singularly 
free from either mud or dust, even when subjected to rather heavy traffic, 
though it is too friable for economical use in such situations. Its per- 
formance is so different from that of the ordinary limestones that an 
analysis is appended : 

Lime 60,20 

Alumina 11.22 

Silica <j.l8 

Magnesia 10.45 

Carbonic Acid 8.00 

Water 4.00 

100.00 

Macadam. 
Roadways surfaced with broken stone have been in use for a long 
time, but Macadam, about the end of the last century, systematized their 
construction and maintenance, effecting such an improvement in English 
roads that his name seems indissolubly connected with roads of this class. 
His plan seems to have been essentially to have a well drained, uniform 
road bed for the reception of small, clean stone of uniform quality applied 
in thin courses, deprecating any addition of earth, clay, chalk, or other 
matter that will imbibe water and be affected by frost, under the pretense 
of binding it. 



68 CONSTRUCTION AND MAINTENANCE OF ROADS, 

He held that a surface of an inch square or a stone 6 ounces in weight 
was of the maximum size for road metaling, anything larger than that 
being mischievous, and that lo inches of solid Macadam was sufficient to 
•carry any load, rather preferring a soft substratum, saying that the cost of 
maintenance on a morass was to the cost on a rocky foundation in the 
ratio of 5 to 7. 

Telford differed from Macadam in his views, how much may be best 
seen from one of his specifications taken from Parnell's Treatise on 
Roads: London, 1833, p. 1^7 et.seq.: "Upon the level bed prepared for 
the road materials a bottom course or layer of stones is to be set by hand 
in the form of a close, firm pavement. They are to be set on their broad- 
est edges lengthwise across the road, and the breadth of the upper face is 
not to exceed 4 inches in any case. All of the irregularities of the upper part 
of the said pavement are to be broken off by the hammer, and all the inter- 
stices to be filled with stone chips firmly wedged or packed by hand, with a 
light hammer. The middle 18 feet of pavement is to be coated with hard 
Stone as nearly cubical as possible, broken to go through a 2 j^ -inch ring, 
to the depth of 6 inches, 4 of these 6 inches to be first put on and 
worked by traffic, after which the remaining 2 inches can be put on. The 
.work of setting the paving stones must be executed with the greatest 
care, and strictly according to the foregoing directions, or otherwise the 
stones will become loose, and in time may work up to the surface of the 
road. When the work is properly executed no stone can move : the 
whole of the materials to be covered by i % inches of good gravel, free 
from clay or earth." Of which Parnell says, " The binding which is re- 
quired to be laid on, on a new-made road, is by no means of use to the 
road, but, on the contrary, injurious to it. This binding by sinking be- 
ween the stones diminishes the absolute solidity of the surface of the road, 
lets in water and frost, and contributes to prevent the complete consolida- 
tion of the mass of the broken stones." 

As regards the foundation. Macadam seems to have the engineers of 
France and England mostly on his side. In this country, it is believed 
engineers generally prefer a Telford foundation. Neither Macadam or 
Telford used a roller, both depending on the grinding action of the 
wheels of wagons to compact their roads ; and it was probably to lessen 
the brutal pulling through loose metal that Telford used his coating of 
gravel. 

Road rolling was first brought prominently before English readers by 
Sir John F. Burgoyne, in a paper written in 1843 (which is reproduced 
by Law & Clark). And the best American practice very fully indorses 
his views. He recommends a weight, as the greatest attainable, of 261 
pounds per inch run of roller, the use of stone dust or sharp gravel for 
binding and watering. His opening sentence, "the importance of rolling 



CONSTRUCTION AND MAINTENANCE OF ROADS. 69 

roads, either newly constructed or when subjected to extensive repairS;. 
seems never to have been duly appreciated," is still true in England, for 
the writer saw loose stone kicking about Great George street, in front of 
the Institution of Civil Engineers, for over a month. 

— It may here be said that writers on roads have not always kept the 
differences between the possibilities of construction of the three types of 
Macadam roads (viz., traffic made, horse rolled and steam rolled) suffi- 
ciently before their readers. The grindmg action of w^heels will pack the 
hardest stones of proper size, and make a firmer roadbed than if a softer 
m.aterial is used for binding, but about one-third of the material is worn 
out in the operation, to say nothing of the wear on horses and wagons^ 
On account of the digging action of the horses' feet when drawmg heavy 
rollers, horse rollers will only compact and bind the softer rocks, without 
the aid of bindmg material, and no steam roller known is heavy enough 
to bind trap and the harder granites, without such aid. 

The only circumstance that can justify an engineer in depending on 
traffic to make his road (except in the case of small, thin patches) is an 
inability to procure a roller ; and then the material should be applied in 
very thin layers, for, in addition to the waste of material, the cost of rak- 
ing and leveling a new^ road will nearly equal the cost of horse rolling, 
the surface will never be as good ; and, as dung and dust will be ground 
in with the stone, it will be more affected by wet and frost. In addition,, 
as a road is made for econom.y and convenience of transportation, the 
damage to horses and vehicles should not be allovred, even if it made 
a better road. 

While a horse roller will make a murh better road than traffic will, 
it is inferior to a road rolled by steam rollers, for about 260 pounds per 
inch run of roller seems to be the greatest weight practically attainable 
by horse rollers, which is not sufficient to make a road of trap and the 
harder stones, without the use of some softer materials as binding, which 
presents the objections stated by Parnell, even under the most careful 
system of application. 

With a steam roller the weight applied can be made equal to the 
requirements. The horses' feet do not cut up the metal almost as fast 
as it is arranged and compacted by the roller. Hard binding can be used, 
making the roadbed nearly homogeneous and impervious to water, pre- 
venting movement of the stones on each other. Lastly, the frictional 
action of the driving wheels arranges and compacts the stones better 
than a greater rolling weight does, making, in fact, an entirely different 
wheelway in its wearing and sanitary aspects. 

The best horse-rolled road known to the writer is the Southern Boul- 
evard, built by Wm. E. Worthen, Member of the Society. The earth 
was compacted by rolling, on which 2}^ inch trap was placed in one 



^o CONSTRUCTION AND MAINTENANCE OF ROADS. 

6-inch and one 4-inch layer, when both layers were compressed as far as 
possible by the use of 2-horse rollers ; 1% inches of screenings were 
spread over and rolled in. As water was not easily attainable on the 
line of the road, the screenings were thoroughly wet before they were 
carted to the road. This wheelway, which was fourteen or fifteen feet 
wide, stood seven years, almost entirely without care, under a heavy cart- 
ing traffic and a good deal of light driving. But the road was never as 
solid as those made with steam rollers and properly puddled, opening more 
with the frost, and having more loose stones on it. 

The writer built some horse-rolled road on an old Macadam road 
which was substantially worn out. The material was a syenitic gneiss 
quite hard, and broken by hand to pass through a 2-inch ring. It was 
generally laid on 6 inches thick, in one course, though where the old m.etal 
was mostly gone, two layers of stone were used. The rollers were 6 feet 
long, weighing about 2 tons light and 3_J^ loaded. They were used with 
2 horses light and 4 horses heavy. The stones, which were broken on the 
side of the road, were handled with lo-tined forks, the tine 14 inches long, 
I X inches apart, known as "tanners' forks." These forks, with a little 
care on the part of the laborer, left nearly all the dust and small stone 
behind (the average wear of tines was one inch for 300 cubic yards 
handled), so that the stones went into the road fairly clean, where they 
were rolled ; the shoulders being at the same time made up with good 
earth, until they were fairly compact, when the dust and small stones 
left by the forks were spread on the surface, which was again covered 
with about % of an inch of preferably clayey soil, where it was procurable, 
which was rolled thoroughly. If the binding was sufficiently damp, the 
road stood very well, showing few loose stones ; bnt when it was too dry 
or the earth was washed into the body of the metal by heavy rains, the 
work was not at all satisfactory. 

The labor account per mile of wheelway, 14 feet wide, equal to 8,213 
square yards, on which 1,260 cubic yards of broken stone were placed, 
was as follows, the days being 10 hours each : Spreading and forming 
material and loading dirt for shoulders and binding, with sweeping the old 
Macadam clean, but no picking, 229.5 days' labor. Twenty-four days 
were occupied rolling, 13.2 with 2-horse and 10,8 with 4-horse teams. 

This road, with the shoulders, was 18 feet wide, and the teams trav- 
eled at the rate of 2 miles per hour ; allowing 90 per cent, of the time 
as productive, the roller passed 144 times over the surface. The mean 
weight of the rollers per inch run was only 75 lbs., and the maximum 
100 lbs., a weight altogether too light for either economical or thorough 
work. 

One end of this road was on a hill, with a rise of no in 1,500 feet ; 
the maximum grade being at a rate of 8 per 100. It was not judged ad- 



CONSTRUCTION AND MAINTENANCE OF ROADS. 71 

visable to depend on natural moisture for the binding-, and a steam pump 
was procured, by the aid of which the metal was made thoroughly wet 
before the bmding was applied. The binding used on the hill was a light 
loam ; but considering the grade, the finished wheelvvay was as good as 
when heavier loam had been used, relying on the moisture in it. 

In England there does not seem to be any well-established system of 
road making. Some of the borough surveyors apparently do not believe 
in any rolling at all ; others, after caref nlly picking up the old roadbed, 
put on the stones, and after more or less traffic has passed over it, put on 
a 5-ton roller 5 feet long, drawn by 4 to 6 horses. The binding called 
" hoggin," which is a loam with coarse sand and gravel in it, is apparently 
not always applied in the case of repairs. Appendix No, i is referred to 
for specifications for a new road. 

The repairs of the wheelway of the Victoria Embankment were made 
by first thoroughly picking up ihe old roadbed and then coating it with 
clean Guernsey granite, hand broken, to go through a 2^ inch ring, 
entirely free from dust and debris, and nearly so from small stone, 
Guernsey granite is about as hard as a trap. It was rolled with 15-ton 
Aveling & Porter's rollers. When compacted, hoggin was added in suffi- 
cient quantity, and with enough water to flush the material into all the 
interstices and leave a surplus about the thickness of grout on the surface* 
which was swept with brooms in front of the rollers. The same system 
was employed at Russell Square and Bedford Place. 

This did not make a good Macadam road ; the hoggin acted as a 
lubricant, allowing the stones to work on each other under the traffic. 
There were loose stones on the road ; five weeks after the road was com- 
pleted, a kick would move the stones in front of it for fully a foot ; when 
the surface was drying, the outlines of many of the stones could be seen 
by the cracks in the mud covering them ; the angles of the stones were 
already wearing off, and after a rain, on sweeping the road, the gutters 
were filled with mud 4 to 6 feet wide. 

It was said that dissatisfaction was felt with this system, and during the 
past summer an effort was made to make a road simply by rolling, without 
the aid of any binding. The success was no greater than that of Mr. 
Grant, 20 years ago, in the Central Park. 

In Liverpool a mixture of broken stone and coal tar pitch is laid — 
one ton of pitch that will just run at 100° F., is mixed with 70 galls of 
dead oil, and added, hot, to 5 cubic yards of stone. The stone is dry, 
but not heated ; the mixture is rolled with a hand roller in short lengths. 
The surface is very good, making a favorite road for bicycle riders, 
and it can be swept without danger of dislodging stone, but it does not 
seem to have the wearing qualiiies of a well puddled trap road. Some 
laid three years in Basnat street, now requires pretty extensive repairs. 



72 CONSTRUCTION AND MAINTENANCE OF ROADS. 

In Scotland, a concrete has been used with Portland cement, for bind- 
ing ; the surface was very good, but when the road commenced to break 
it went to pieces very fast. 

M. Malo speaks of the Macadam in Paris as follows : " Day by day 
they try with incalculable efforts to perfect Macadam. They have per- 
fected their watering in summer and sweeping in winter ; they have sub- 
stituted, at great cost, granite in place of limestone ; they have multiplied 
their road laborers ; each morning the devastacions of the day before are 
repaired with incredible rapidity, but when the stream of traffic again covers 
the street, the Fcourge {fieau) recovers its rights, and during 300 days of the 
year the roadway becomes an ocean of mud or a mass of infected dust," 
In other words, a poor system of construction, but probably the most 
thorough system of maintenance to be found anywhere. A. Debauve, in 
his "Manuel de I'lngenieur," after speaking of the immense capital invested 
in the old Roman roads, says : " The tendency now is to have the thick- 
ness only that which is necessary for resistance, to suppress the founda- 
tion, and, in one word, to economically establish the roadways and maintain 
them afterward in a tit state by incessant repairs, which the ancients did 
not know of." 

In Paris the Macadam roads are composed of water-worn flint pebbles, 
which are compacted by ramming with a rammer 8 inches in diameter, 
weighing 70 lbs., and horse rolling with the aid of sand and water, ineu- 
liere — a kind of burr mill stone — and porphyry, the two latter are gener- 
ally steam rolled. These materials are used, according to Debauve, in the 
following proportions, viz. : flint, 10 per cent. ; meuliere, d'j per cent., and 
porphyry, 23 per cent. 

Macadam roads in Paris, as in London, are the roads of luxury. On 
many streets, the centre, for a width of 19 feet, is covered with Macadam^ 
while the sides, for a width of 13 feet each, are paved with stone sets or 
asphalte. The Avenue des Champs Elysees, Place Concorde, and some 
of the Quais are of flint ; other of the Ouais and Rue de Rivoli are of 
harder stone, while the Avenue de I'Opera, Boulevard Haussmann, etc., 
have Macadam only in the middle. 

The French, who use the Gellerat roller in Paris, specify a maximum 
weight of 448 lbs. per inch run, and a m.aximum speed of 2.3 miles per 
hour. The rolling is done by contract (the city furnishing the water) at a 
rate per ton mile, varying from 1 5.26 co 7.63 cents, according to the amount, 
with an increase of one-third in price where the grade exceeds 6 per cent. 

The thickness of metal rolled varies from 12 inches on new roads to 
2 inches on old. It is maintained that the work of compacting a cubic 
yard of the same stone is independent of the thickness when that varies 
between 2 and 6 inches, and is from 2.7 to 3.27 ton miles per cubic yard. 

From a table (p. 308) m the notice of the objects, etc., exhibited by 



CONSTRUCTION AND MAINTENANCE OF ROADS. 75 



the city of Paris at the Exhibition of 1878. it is seen that the mean weight 
per inch run of the steam rollers is 448 and 336 lbs., and for the horse 
rollers 263 lbs. Also that the ton miles necessary to make a square yard 
of porphyry wheelway, or to compact a cubic yard of the same metal, are 
as follows : the mean for the two models of machines weighing 448 lbs. 
per inch run was, per square yard, with thickness of 3.9 inches, 0.41 ton 
miles ; while for the roller of 336 lbs., with a thickness of 2.8 inches, 0.234 
ton miles were required, or 3.78 and 2.99 ton miles per cubic yard respect- 
ively ; and for horse rollers, where the thickness was 2.6 inches, the ton 
miles required were 0.194 per square yard and 2.69 per cubic yard. The 
amounts consolidated per ton per hour are in the following proportions : 
467 for the heavy rollers, 539 for the light roller and 297 for the horse 
roller, and the number of passages of the rollers were 98.5, 75 and 92. 

It appears from these tables that the smaller weight is the more advan_ 
tageous, and that horse rolling is cheaper than steam rolling ; it is added. 
that, on account of their superior celerity, the steam rollers are almost 
exclusively employed. 

No statement is made as to the relative wear of stone rolled by the 
different machines. 

About 24 per cent, of sand is used for binding. The surface is allowed 
to wear down until 2 to 6 inches of metal is put on. 

Repairs were being made on Boulevard Haussmann by a 5-inch layer 
of meuliere, very nicely hand broken to pass through a 2%-mQh ring, free 
from dirt and small stone ; the roller had a weight of 360 lbs. per inch- 
After a few passages had been made over the stone, very clean sand v/as 
spread on, which was shortly wet by a hand hose. The water was not at 
first applied in sufficient quantity to flush the sand thoroughly into the 
interstices, but the sand was just damp enough to pick up the stones. 
The speed of the roller was thought to be fully 2% miles per hour. The 
binding was not so thoroughly wet as on the Victoria Embankment, nor 
was the metal rolled as much. When the street was thrown open to traf- 
fic the consolidation was about at the point at which in this country we 
would commence applying screenings, stones were picked up by the 
wheels, and a light kick would move the stones for from i to i>^ feet in 
front of it. 

On the Avenue de I'Opera, the centre of which is covered with broken 
porphyry, the stones presented the same evide-nces of motion on each 
other, mentioned as seen on the Victoria Embankment. 

In New York City there arc, including St. Nicholas avenue, 27.99 
miles or 921,400 square yards of steam-rolled M-icadam roads, besides the 
horse-rolled roads in the Central Park and the Twenty-third and Twenty- 
fourth Wards, of which 17.75 miles or 71 8,200 square yards are on Telford 
foundations. They were commenced in 1869, and mostly finished in 1876, 



74 CONSTRUCTION AND MAINTENANCE OF ROADS. 



The first had a 5-inch layer of gneiss laid on the Telford, on that a 
5-inch course of trap, both broken to go through a 2>^-inch ring. The trap 

was and is machine broken, and the screen- 
I ings, /. e., dust and stone that passes 

1 _c through a i-inch or iX-inch aperture, are 

j -| used for binding. At first it was held that 

these should be used as sparingly as pos- 
sible, but experience has shown that the 
roads wear better and have less loose stones 
on them when the interstices ai e fully filled 
with screenings, and the size of the stone 
in the top course is preferably from i to 
1% inches. The general practice now is 
to put on the stones in two courses when 
the thickness, compacted, is 6 inches or 
more, and roll the first course until it will 
settle no more, then add the last course, and 
after it has settled, screenings are added, at 
first coarse and then fine, and after thor- 
ough rolling, the whole is puddled by a co- 
pious addition of water. This is accom- 
plished more thoroughly and satisfactorily 
in hot, dry weather. After the road is pud- 
dled % X.0 Yz inch of screenings are spread 
over it, and after drying an hour or so the 
traffic is turned on. 

For the old style of construction Sixth 
avenue, between One Hundred and Tenth 
street and Harlem River, may be taken as 
a type, having the materials and courses as 
above mentioned. It was rolled with 
Aveling & Porter's 15-ton rollers, of the old 
pattern, in which the weight is nearly 
equally divided between the steering and 
driving wheels, which cover 6 feet, giving a 
bearing weight of 467 lbs. per inch run. 
As near as can be ascertained, 24 6-10 
hours, at iX miles per hour, were occu- 
pied in rolling 1,000 square yards, giving 
' for the work done 0.553 ton miles per square 

yard, 2.246 ton miles per cubic yard, and 129.8 trips of the roller over the 
surface. 
VAvenue St. Nicholas, which, as mentioned above, was made from Roa 




CONSTRUCTION AND MAINTENANCE OF ROADS. 75 

Hook gravel, had a rubble foundation, and it was intended to have 6 
inches of compact gravel, but the foundation settled so that in some in- 
stances the gravel is 14 inches thick. The practice was to lay the gravel 
on and wet it thoroughly over night. It was rolled the next day until the 
water was forced to the surface. A 15-ton roller was employed about 26 
hours per 1,000 square yards, besides some horse rolling. A little hard 
pan was used for binding. The intention was to make a road for ^ast 
driving, but the surface was as hard as that of a Macadam road, though 
much smoother. 

The data for these two avenues depend on the memory of the engineer 
of the roller, and are approximate only. 

The Telford Macadam on Fifth avenue has 8 inches of Telford, 3 
inches of 2>^-inch trap, 4 inches of 2-inch trap, i inch of coarse screenings, 
and one-half inch of fine screenings, when completed. The wheelway is 
40 feet wide between curbs, with 4 foot gutters on each side, of trap 
blocks. 

Mr. F. H. Hamlin, for some time Engineer in the charge of Roads and 
Streets in New York City, to whom I am indebted for these data, intended, 
by the use of the 1%. inches ot screenings, to have the road as smooth and 
pleasant for riding as Avenue St. Nicholas, without the tendency to mud 
in wet weather. The work was let in two contracts, at $1.30 and $1.49 
per square yard. The average time employed setting a square yard of 
Telford was 20^ minutes. Spreading the stone and screenings, per 
square yard, i 2-10 minutes. About 58 6-10 hours rolling were given per 
1,000 square yards ; and the work done, allowing the effective speed to 
have been 1% miles per hour, was 1.099 ton miles per square yard, and 
4.709 ton miles per cubic yard of compacted material, if there had been no 
settlement, but there was an unascertained settlement. 

These roads are maintained by spreading very thin layers of tine Roa 
Hook gravel over them and watering. The first roads were built with 
an idea that as small a quantity of screenings as possible should be used, 
and in dry weather the stones, which become prominent by wear, are 
liable to kick out ; the fine gravel prevents this, and by retaining water 
sprinkling is not necessary so often. The fact that the travel concentrated 
near the gutters, where this gravel, by the action of rain, becomes thickest, 
in connection with the demands of owners of fast horses, who wished a 
softer road-bed, led Mr. HamHn to cover one of them with a coating three- 
eighths of an inch thick, consisting of three parts of coarse sand and one 
part of strong clay. This has been on the road through two winters and 
the road-bed is still firm, and it has been applied to others. 

Under Mr. Hamlin's charge the average cost of maintaining these 
roads has been 4 2-10 cents per square yard per annum for the labor and 
material of road covering, cleaning and sprinkling, with incidental repairs 



/ 



76 CONSTRUCTION AND MAINTENANCE OF ROADS. 

and supervision. None of them have been resurfaced with broken stone 
excepting a portion of the Western Boulevard, the first built, and two or 
three patches of loo feet or less in length, which cost 46 cents per square 
yard. 

It is very difficult to estimate the traffic on these roads. On a fine day 
3,000 vehicles may pass over them, while at other times there may be not 
more than one-tenth of that number. 

In repairing the Southern Boulevard, mentioned above, the trap broken 
to go through a 2-inch ring was laid on 6 inches thick in one course ; 
38 2-10 uours' roiling was given per 1,000 square yards. Allowing the 
speed to have been 1% miles per hour, the work done on it amounted tO' 
0.859 ton miles per square yard and 5.177 ton miles per cubic yard ; 201 
trips were mide over the surface. The Macadam was 15 feet wide, and 
some of the rolling was on the shoulders, though probably not enough to 
affect the result materially. The work was done in Jnly and August, and 
a little less than 0.6 cubic feet of water per square yard (3,5 cubic feet per 
cubic yard) were used in compacting and puddling. About one-third 
screenings were added. Those portions of the road that had the most 
work done on them are now in the best form, after nearly two years with- 
out any care ; and, generally, the more thoroughly the trap roads were 
j-olled the better do they wear. 

It should be understood that there was no counter on the wheels of 
the rollers, and the speed is the result of estimation, interfering with 
accuracy in the estimate cf the number of ton miles performed. The 
rollers used fn the above mentioned works were 15-ton Avehng & Porter's 
(old pattern), and though they are understood to bear equally on the driv- 
ing and steering wheels, the writer thought the driving wheels nearly twice 
as effective as the steering wheels. 

The superiority of the American Macadam roads is partly due to the 
greater amount of work put upon them ; the binding, which is of the same 
hard material as the metaling, almost completely fiJs the interstices between 
the stones, and the entire mass is thoroughly compacted and nearly homo- 
geneous. It is only while the frost is coming out of the road in the spring 
that the stones wear upon one another at all. The process of puddling 
gives a very smooth, hard, firm surface, resistant alike to wear and the 
infiltration of water, which is of equal advantage to the stabilfty of the 
foundation and from a sanitary point of view. By the use of the steam 
roller the stones are compacted with a small amount of wear to their angles 
and an entire freedom from mud and dung, their only weak point being 
that in long-continued dry weather the larger stones are apt to get dis- 
lodged from the surface, some moisture being necessary for the full cohe- 
sion of the binding. No amount of wet weather, unaccompanied by frost, 
seems to injure them, unless mud works up through the foundation, and 



CONSTRUCTION AND MAINTENANCE OF ROADS. 77 

their imperviousness under the most disadvantageous circumstances is 
well illustrated by the practice of Mr. Hamlin, as cited above. 

The English roads are rolled less, and the binding, though cheaper in 
■cost and the matter of rolling and spreading, is, when thoroughly wet, to 
a great extent an element of weakness to the roads, allowing a large part 
of the wear to be internal, and failing to hold the stones from dislodgment, 
either by the wheels of vehicles or the brooms of the sweepers. When 
dry it can have neither cohesion nor resistance, its use being confined to 
the time it is slightly damp. 

The roads in Paris seemed to be less thoroughly compacted than in 
London, but the binding was better, and if it had been applied dry, after 
the stone >\'as nearly compacted, and only wet at the last rolling, it would 
probably be more effective. As it was, the grain of the sand seemed to 
have been broken down dunng the rolling of the stone, and as, like the 
English made roads, the stones move on one another, it must be still more 
thoroughly ground up. 

The maintenance of roads in Paris is much more effective than in 
London. It consists essentially in washing rather than sprinkling them, 
and sweeping the mud and debris of the surface into the gutters, where it 
is washed with a copious flow of water, the mud and fine sand going into 
the sewers, the coarser sand being retained for use on the streets. "Most 
of the work is done at night and in the early hours of the morning. While 
there is on the average (judging from the amount of mud relative to the 
traffic) rather more wear than in London, no loose stones were seen on 
the streets, except when newly mended, men apparently being always 
present with brooms, rammers, and sand, to repair any place that showed 
signs of weakness. On the Avenue des Champ Elysees, and other flint 
roads, the surface was often swept with birch brooms having long and 
slender twigs. 

In London the maintenance is neither so constant or skillful ; the roads 
are watered in dry weather, and swept or scraped in wet, with an occasional 
addition of sand or fine gravel. 

There seems to be no accessible accounts of the cost of repairs and 
maintenance in London. W. S. Till, the Borough Surveyor of Birming- 
ham, in one of his reports, says : " Mr. Howell, Surveyor to the Vestry of 
St. James, Westminster; informs me that the cost of maintaining, etc. 
the surface of Regent street, London, which may be considered one of the 
best Macadamized roads in the Kingdom, and in which nearly every 
description of pavement has been tried, is $0.87 per square yard per annum 
it has, however, been much higher." It is not known whether Regent 
street was then steam or horse rolled. 

In Paris, the expense of maintenance had reached on some of the streets 
16 francs per square meter ($2.57 per square yard) per annum, and it 



78 CONSTRUCTION AND MAINTENANCE OF ROADS. 

was resolved to pave all but the middle 23 feet, in streets 48 feet wide, 
and to pave narrow streets and gutters, and in 187 1 it was resolved to pave 
streets where the annual expense of maintenance was over 48 cents per 
square yard, excepting those avenues which are used by carriages of 
luxury. This, however, was not fully carried out. 

Many adverse criticisms are made on Macadam roads by parties who 
judge of their value mainly from reading statements regarding European 
Macadam. A well-made trap road, when properly watered and main- 
tained, is, after an earth road, the pleasantest and safest road known. In 
this locality a road 15 feet wide would give suburban residents the same 
easy access to their railroad stations in the worst winter weather as in 
summer. And for streets of residence, where the inhabitants would keep 
them free from garbage, both for quiet, safety to horses, and on sanitary 
grounds, they are preferable to the ordinary paving. 

It is possible that with thoroughly compacted and bound roads, the 
English and French engineers would look with more favor on Telford 
foundations, for with the roads we make, the wear between the Macadam 
and Telford must be very slight, the pressure of a wheel being spread 
over a large surface. They are preferred here because they give an equa 
depth of foundation more cheaply than with broken stone, and as in this 
country municipal appointments of engineers are sometimes influenced 
by political considerations, the general desire is to build as solidly as pos- 
sible. 

One objection that may be urged against the Telford foundation is the 
fact that it does not have a solid bearing on the earth roadbed, and when 
the road is worn thin the spaces between the stones may become filled 
with water and mud, which will work through the foundation into the 
broken stone, hurrying the disintegration of the road. 

The English engineers often use "hard core," a mixture of brick 
rubbish, old plastering and broken stone, on a clay soil, to prevent the mud 
working into the metaHng. 

The result was accomplished by the use of six to eight inches of fine 
sand on Mott avenue, New York, which was built at the joint expense of 
the city and private parties. The regulation of the s'jrface required a 
maximum cut of two and a half feet and a fill of four feet ; the soil was a 
heavy loam, thoroughly saturated by the fall rains, which continued until 
the work was completed, and it was desirable to Macadamize it immedi- 
ately. Rough gneiss rock was placed on the layer of sand and rolled to an 
even surface, with a thickness of about eight inches, and on th^t a scant 
six inches of loose 2-inch trap, to which thirty per cent, of screenings were 
added. The bottom was very treacherous ; on about half the road it was 
not safe to stop the roller, which broke through in two instances in spite 
of the care exercised. Nor could the road be rolled long in one place ; but 



CONSTRUCTION AND MAINTENANCE OF ROADS. 79 



as soon as the surface began to weave in front of the roller it was given a 
rest, and the roller taken to another part of the road. In spite of this the 
fOad was compacted and the surface puddled satisfactorily, except in one 
or two small patches. It has stood the freezing and thawing of two winters 
without receiving or requiring any attention. 

It is held that the success of this operation, so contrary to the teachings 
of the books, was due to the layer of fine sand being impervious to the 
mud, which without it would have been over the top of the Macadam a 
long time before it was puddled. 

The deductions of the French engmeers from the table cited on page 
12 should have been strengthened or modified by a statement of the wear 
of the different work done. And their principles of road construction are 
dissented from, because the writer believes that the horse-roller made road 
does not differ so much (after both are compacted) in wearing value from 
the road specified by Macadam as it does from the road properly made by 
a steam roller ; that all binding should be fully as hard as the stone, and 
that the better road is made with the heavier roller per inch run, as far as 
his experience has gone, /. e., up to 460 pounds. And, in addition, up to 
that weight the ton miles rather than the load should be altered on ac- 
count of the greater or less hardness of the rock employed for road con- 
struction. 

It is believed that no one who has used the twa styles of 2-ton rollers 
mentioned, viz., 3 feet and 6 feet long, doubts that the 3-foot roller will do 
better work than can be accomplished by the 6-foot roller without leading. 

Under the writer's direction the same quality of syenitic gneiss men- 
tioned on page 9 was rolled with a 15-ton steam roller, with binding of the 
same quality in both cases. There were only about 200 cubic yards of it, 
and on account of the traffic passing, it was impossible to keep an exact 
account of the work done, but the road is very satisfactory, and from it 
the writer thinks that a few passages of the steam roller over the horse- 
rolled road would add materially to its life, besides greatly reducing the 
number of loose stones on its surface. 

Some refuse Westchester marble (a very soft rock) was delivered on 
some of the roads at about 25 cents per cubic yard, and hand broken in 
place at the rate of about i cubic yard per hour. A portion was rolled 
before any traffic went over it, some after about two weeks of traffic and 
some after six weeks ; of the rest, part was horse rolled and part com- 
pacted by wheels ; the quality of the stone, traffic, etc., were very nearly 
the same ; that not rolled by the steam roller soon wore into holes; the 
first mentioned is, after standing two winters, in very fair surface ; the 
others decreasing in the order in which they are mentioned. This dif- 
ference is so noticeable that any one could pick out their sequence as men- 
tioned. 



So CONSTRUCTION AND MAINTENANCE OF ROADS. 





Shortly before this, however, the writer very nearly made a mush of 
some micaceous gneiss in trying to reduce the crown of a road covered 
with it. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 8i 

Late in the fall a portion of the Southern Boulevard was repaired with 
2-inch trap, screenings, and a 2-ton horse roller. After the metal was 
compacted a thin coat of clay hard-pan was added, which froze solidly 
that night, and a day or two after was covered with snow which stayed on 
till spring, thus giving it the most favorable surroundings possible. In the 
summer there was but little difference between it and the steam rolled 
part ; but by fall it had commenced to deteriorate, and now its surface is 
but little better than that made seven years before. 

Both the English and French prefer hand-broken stones for Macadam. 
An experienced breaker will make better shaped stones than any crusher 
can, and hand-breaking would afford employment to labor. The hand- 
broken stones mentioned above were delivered by contractors at $2.00 per 
cubic yard ; the men who broke receiving on an average Zi% cents per 
yard. One man was thought to have broken at the rate of 4.5 cubic yards 
per day ; about 6 to average 1]/% yards or more. They stood, using 
hammers weighing 1 1^ to 2 pounds, on very flexible handles. The ave- 
rage of all who worked could not have been much over i yard per day. 

On the other hand, there is not enough fine stone for binding, what 
there is is full of dirt, and machine breaking is cheaper ; the cost of crush- 
ing trap with a Blake crusher, after it is sledged, being understood to be 
less than 70 cents. 

The crown or transverse section of a road should depend on so many 
different considerations that no general rule can be drawn for it. With 
Macadam made from hard material, the less crown, on many accounts, 
the better, as the surface is benefited by being kept damp. In narrow 
\vheelways, particularly, an excessive crown throws all the traffic, as much 
as possible, in one line, whatever the material may be. On the other 
hand, in curbed streets, if the road is too flat, the heavy traffic tends lo 
concentrate near the gutters. The crowns given to dirt roads are in- 
tended to drain off the water, but the longitudinal ruts soon defeat that 
object. 

Transverse profiles of the Western Boulevard and Sixth Avenue, New 
York City, are shown on page 80. On the former, tiiough the transverse 
slope is so slight, it is perceptible to a person riding in a vehicle with longi- 
tudinal seats, but is not noticeable when on a transverse seat. The cross 
section of Sixth Avenue shows the surface as the road was constructed by 
M. A. Kellogg, Engineer, in 1872 and 1873, with the crown at the same 
height as the top of the curb stones, and the figures above the dotted line 
joining the curbs show the average distance of the surface below street 
line, as found by careful levels taken this spring between 123d and 124th 
streets, a point where no broken stone had been added, the wear at the 
crown being 0.15 foot, or about ;^-inch per year. The road is not too 
flat, as it now stands, to shed the ramfall. 



82 CONSTRUCTION AND MAINTENANCE OF ROADS. 

The amount of water the writer found necessary to keep earth or Mac- 
adam roads from becoming dusty, was, for a well mamtained earth road, 
at the rate of 71.3 cubic feet per 1,000 square yards, applied twice in a 
day, or say 143 cubic feet per day. In very hot or breezy weather this was 
not quite enough. 

On the Telford roads of this city, 25 cubic feet, applied four times a 
day, are necessary per 1,000 square yards, say 100 cubic feet per day. 
One water cart, holding 79 cubic feet, waters 35,000 square yards four 
times a day, keeping it free from dust, except during windy weather. 

In Paris about 27 per cent, of the surface is watered by hand hose. 
These are made of iron pipes about dyi feet long, each end supported on 
castors and connected with leather or rubber couplings ; the working end 
being a piece of rubber hose. Its cost is one-half that of watering by carts 
holding 46 cubic feet. 

Stone Pavements. 

The City of New York is largely paved with the Belgian pavement,/.^., 
truncated pyramids of trap set in coarse sand. The sand soon becomes 
saturated with the water and mud of the streets, and the blocks working 
under the traffic become rounded. It is impossible to keep such pave- 
ments in fair surface, and they are as bad sanitarily as pavements can be. 

The pavements now laid are of granite or trap blocks, 4 inches wide, 6 
inches deep, and 8 to 12 inches long. They have parallel sides, and are 
laid in sand, probably form'ng the most efficient pavement ($1.91 per 
square yard), to be found anywhere. The open joints filled only with sand 
are objectionable, however, as formmg receptacles for street mud and 
water. 

The Guidet pavement laid in Broadway, with a foundation of concrete, 
has lasted very well, its increased wear probably compensating for the ad- 
ditional cost of the concrete foundation. 

In Paris, the new pavements are of Gris, a hard sandstone, which is 
neatly dressed in blocks, 4 to 5 inches square, and laid either in sand or 
mortar, and porphry, about 4 inches wide, 6 inches deep, and 8 inches long, 
generally laid in mortar. 

The best granite pavements are found in England. In London, where 
the soil is clay, the usual practice is to lay a foundation course of " hard 
core " which is well compacted by rollmg, &c., and the stones are set on 
this in two inches cf sand. The better class of pavements, on clay, have 3 
to 6 inches of hard core, 9 mches of concrete, and two inches of sand. Col. 
Haywood, wbere soil is sand or gravel, puts down 9 to 18 inches of broken 
stone, or 9 inches of concrete, saying that there is little difference in the 
stability of the two foundations, but the concrete is apt to be replaced in a 
more satisfactory condition when the street has been opened. 



CONSTRUCliON AND MAINTENANCE OF ROADS. 83 

In all the better class of London pavements, the sets are 3 inches wide, 
neatly split out with parallel sides, and set in blue lias lime grout, Aber- 
deen granite being chosen in preference to harder varieties, as it wears 
rough. Though Col. Haywood determined that the duration of the same 
stone varied directly with their size, these narrow sets are preferred, as 
making a smoother road, affording a better foothold for horses, and in- 
creasing the quietness and general comfort. The practice is to take up the 
sets when their surfaces become rounded, and redress them, after which 
they are relaid in streets of secondary traffic. The spalls are useful for 
foundations and Macadam, Col. Haywood estimates the total life of such 
paving stones to be 29 years. 

In Liverpool, Geo. F. Deacon prefers the Welch traps and granites, 
which are rather harder than our trap. The pavement of North John 
Street, which has a traffic of 4,000 vehicles, averaging 3 tons each, per day, 
is of trap blocks, neatly split out, with parallel sides, 6 inches deep, and 3X 
X3X inches on the face, set on 10 inches of concrete; the joints are filled 
with gravel, about the size of a pea, free from sand, and then run with coal 
tar pitch. It had been paved very close, and the sets were so firmly held 
in place that there was hardly any rounding of the surface last winter, 
though it was laid in 1872. The surface was admirable, and showed very 
slight wear, and on sanitary grounds it- is probably unequaled by any 
other pavement, except compressed asphalte, for there can be no percola- 
tion of the surface water. The only signs of failure shown by this pave- 
ment is where the boiler of the " Montana," weighing with its 4-wheeled 
truck 59 tons, passed over it, crushing some of the sets, and showing that 
stones 3X inches square on the face, are not large enough to stand loads 
of 1 5 tons per wheel. 

Mr. Deacon thinks that the 3X inch square blocks present too many 
longitudinal joints, and now employs sets 3 inches thick by 6^ inches 
deep, and 5 to 7 inches long ; the specification for thickness is that any 4 
of them, when set side by side, shall measure 12 inches, and not more than 
14 inches. It is said the specification is filled without extra cost. 

Wood Pavements. 

In London, the principal wood pavements are Gary's, the improved 
Wood, Henson's, and the Asphaltic Wood. Cary's is laid on sand or 
gravel, a firm foundation being first made. The patent is for dovetailing 
the blocks on their ends, which is held by the inventor to give the pave- 
ment greater stability. The joints are flushed with blue lias lime grout. 
The advantage claimed for this pavement is the ease with which it can be 
repaired, the method being apparently to take out the defective block or 
blocks, cut off the broomed portion that overhangs the sides of the blocks, 
put in enough gravel to restore the surface, replace the block with the 



84 CONSTRUCTION AND MAINTENANCE OF ROADS. 

other face up, and run in the grout. A portion of Cannon street is laid 
with this pavement. It is said by persons on the street to require fre- 
quent repairs. Its power of resisting wear must depend on its founda- 
tion, and it can hardly prevent water from working into and through the 
foundation. 

The " Improved Wood" Company started to make an improvement on 
the Nicholson patent, using two tarred boards, resting on sand, under the 
blocks. Ludgate Hill, and some other streets, were laid on this principle, 
but, under the heavy traffic, the two boards acted Hke a pump, pumping 
the sand up through the pavement. After trying and discarding one 
board laid on concrete, they now lay a foundation of concrete 6 inches 
thick, on which the blocks are placed ; the jomts are filled with pitch and 
gravel. This modification apparently makes a good pavement, as seen on 
Ludgate Hill, where the first pavement has been renewed, and at St. 
Paul's Church-yard. No company now lays boards as a part of its founda- 
tion. 

Under the name of Ligneo Mineral Pavement, a company laid some 
pavement of hard wood, but it proved so slippery that work under that 
patent has been mostly abandoned. The most work seems to be done, at 
present, by the Henson and Asphaltic Wood companies. 

In the Henson pavement the 6 inches of concrete is covered with a 
layer of tarred felt paper, on which the blocks rest, while a strip of the 
same material is placed vertically between each row of blocks across the 
street. Nothing is interposed between the ends of the blocks. After each 
few courses are laid the blocks are driven close together by a heavy maul. 
Hot coal tar and pitch is plentifully applied to the upper surface, after 
which gravel is strewn over it. It will be observed that this pavement pre- 
sents about as small a joint for foothold as is possible, and to meet objec- 
tions on this score, at first about every fifth course had a V-shaped groove 
cut in its top. This has been abandoned by the company, who now lay 
the surface flush, making a road almost free from noise and near- 
ly as smooth as a compressed asphalte pavement. In answer to objec- 
tions to their narrow joints, their engineer asserted that they had 
changed the practice of the other companies in London from 1% ox \ inch 
joints to as near a quarter of an inch as it is practicable to make them, to 
the decided advantage of all pavements. They also assert that the tarred 
felt under the blocks will not wear out, that the pavement is impermeable 
to water, and that it can be more thoroughly cleaned than any other wood 
pavement. This pavement was taken up, for pipe connections, in Leaden- 
hall Street and High Holborn. Although it had been raining in the first 
instance, and raining and freezing in the other, the wood was bright and 
not at all watersoaked ; the felt underneath, however, was considerably 
worn. The claim in regard to cleaning is probably correct. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 85 

The asphaltic wood pavement, laid under the patent of H. S. Copland, 
C. E., has on the 6 inches of concrete a quarter of an inch of tempered 
Trinidad bitumen, on which the blocks are placed ; the joints across the 
street, which are kept between a quarter and an eighth of an inch, are run 
with a softer bitumen for about 2 inches, and flushed with lias lime grout, 
the ends of the blocks abutting against each other ; the whole is covered 
with gravel. The pavement, unless cracked by the settlement of the 
foundation, must be as impervious to water as one of asphalte, and should 
stand the traffic very well. On account of its rigid foundation it is more 
noisy than the Henson, and having a slightly wider transverse joint, it 
hardly rides as smoothly after some wear, though the difference would not 
be readily noticed. It should be noticed that the bitumen which is run in 
the joints makes a firm bond with the layer under the blocks, and more 
wood is spoiled in taking up this pavement than any other observed. 

This pavement was first laid in Cannon street, between Abchurch and 
Laurence Pountney Lanes, in July, 1874. It was laid, apparently, with 
joints rather over than under i inch, and in December, 1878, the edges of 
each block had broomed over into the joint ; otherwise the surface was 
good, and I could not learn from any source that repairs had been made 
on it, except when the street had been opened for pipes. The grade is i 
in 90 ; and in 1873 the number of horses passing over it in 12 hours — from 
8 A. M. to 8 p. M. — was 5,350. 

The practice in London is to cover the surface of wood pavements 
several times a year with hard gravel, which is beaten into the ends of the 
fibres by the traffic, tending to preserve the blocks from wear and, it is 
claimed, from decay. The wood used is a species of pine — Baltic fir — harder 
than our white pine and softer than Southern or pitch pine, resembling- 
what is sold in the Chicago markets as Norway pine ; it is better seasoned 
than the pine generally used by house carpenters ia this country, and it is 
usually laid without being creosoled, the borough surveyors claiming that 
the difficulties of inspection are increased by creosoting ; but as far as 
noticed, for renewals and repairs, which are made by the companies under 
their contracts for maintenance, creosoted wood is used, their managers 
saying that they expect it to add to the wearing qualities of the wood as 
well as to protect it from decay. The concrete, usually covered with a 
thin coating of cement mortar, is made of one part of Portland cement to 
six parts of Thames ballast, which varies in size, from sand to pebbles 
three-quarters of an inch in diameter. 

It is rather difficult to arrive at the durability of either wood or asphalte 
pavements in London, as Col. Haywood, the City Engineer, lets them at 
a certain price, with a provision that they shall be kept in repair for a term 
of years at a certain price per square yard per annum, a good pavement 
being turned over to the city at the expiration of the contract for main- 



86 CONSTRUCTION AND MAINTENANCE OF ROADS. 

tenance, the contractor, in the meantime, replacing the entire roadway, if 
necessary, as will be noticed under the head of asphalte. This plan has 
worked so well in the city that the surveyors for the vestries have gener 
ally adopted it, so that, in London, the wood paving contracts are usually 
let with the same length of maintenance as for compressed asphalte, and 
at about the same price, viz., at a first cost of from $4.38 to I3.90 per 
square yard, including foundation, but not excavation. They are kept in 
repair for two years at the contractor's cost, and at the rate, depending on 
^he amount of traffic, of from 36^ to 18X cents per square yard per 
annum for the succeeding fifteen years. 

From the report of Col. Havwood to the Commissioners of Sewers of 
the City of London upon asphalte and wood pavements, 1874, page 38, 
et seq., we find that the greatest duration of any wood pavement was in 
Mincing Lane, nineteen years and one month ; the average cost per square 
yard per annum having been, in that instance, thirty-five and one-half 
cents, while the average cost of three heavy traffic streets had been sixty- 
three and nine-tenths cents. He concludes that, with necessary repairs 
wood pavements will last ten years in London. 

Law & Clark's Roads and Streets, page 239, gives the wear of three 
wood pavements at three-tenths of an inch per annum under a traffic 
averaging 362 vehicles per day of twelve hours for each foot in width of 
the street. Mr. Clark says it is claimed, in some instances, blocks have 
worn down in London to a depth of two and one-half inches (the Wells 
street pavement was only two inches thick, before removal), and suggests 
eight or nine inches as a better depth than six inches, now universal. 
The blocks of the Mincing Lane pavement, w^hich lasted nineteen years, 
were nine inches deep. If we assume that the blocks are six inches deep, 
and that the road v/ill not break up until they have worn down three inches, 
there seems no reason why a thoroughly creosoted wood pavement, laid 
with narrow joints, on a sufficient bed of concrete, wiLh a water-tight 
stratum interposed, should not wear for about ten years in our streets of 
heaviest traffic with a small amount of intelligent maintenance. 

There have been several charges made against wood pavements, which 
are mentioned here, not as a matter of information, viz., that they soon 
become full of holes, are impossible to clean, are difficult to replace when 
the street is opened, and that by their rotting the health of the community 
is endangered, to which may be added that for only a short time do they 
present any barrier to the saturation of the soil by surface water. 

The general practice, as far as observed by the writer, in this country 
has been to Xd^-^ green or wet pine blocks, more or less thoroughly dipped 
in coal tar, on a bed of sand, not always thoroughly rammed, with or 
without the interposition of a tarred pine board, with transverse joints 
from one to one and one-half inches wide filled with gravel and coal 



CONSTRUCTION AND MAINTENANCE OF ROADS. 87 

tar, which was theoretically thoroughly compacted. Omitting those 
which, without the slight pretense of a i-inch board for foundation, 
speedily become a wood Macadam, the fifst failure was from the 
blocks rotting on the bottom in patches, so that the surface would 
first be found to be sheared down by a heavy load ; and on taking out 
the blocks they would be found sound on their tops, where the gravel 
had been driven into them by the traffic, and also a sound film of about 
the thickness that tar could be expected to penetrate a wet block, the 
inside being rotten. In other cases, however, when the layer of sand 
was too thin, the mud worked up through both boards and blocks, 
reducing everything to about the state of those having no boards under 
them. 

A layer of concrete, covered with Trinidad bitumen, will effectually 
stop the mud from coming up, and any percolation of the surface water 
into the soil through the pavement ; the narrow joints, by preventing the 
edges of the blocks burring over, will both tend to keep the surface 
smooth, lessening the shocks of the wheels, and greatly facilitate all the 
operations of cleansing. Creosoting, by the preservative and antiseptic 
properties of the dead oils used in that process, will probably keep the 
timber from decay, so that nothing but abrasion need be feared, and the 
sanitary objections to decaying wood will be removed. 

The following note of some experiments by E. R. Andrews (pub- 
lished in " Engineering News ") shows the efficacy of creosoting for pro- 
tecting wood from moisture. 

The following are the results of some careful experiments with differ- 
ent varieties of wood, half of the specimens being simply dried and the 
others creosoted, to ascertain to what extent wood is rendered water-proof 
by creosotmg. The specimens were soaked durmg two days m water, be- 
ing carefully weighed before and after soaking : 

Percentage of 
watei' absorbed. 

Spruce, creosoted 0236 

0306 

" dried only 1764 



" Burnettized 2500 

Hard pine, creosoted 0000 

" dried onl}' 1 6oO 

Oak, creosoted 0625 

'• dried only 2000 

White birch, creosoted 1240 

" dried only 4300 

Cottonwood, creosoted 3470 

" dried only 7140 

Black gum, creosoted 1250 

" dried only 1 .0000 

Sesquoia Gigantea (great tree of California), creosoted 0000 

'■ " " dried only 4722 

In the rooms of this Society are creosoted fir ties from England that 
have been in the track for 20 years, and apparently justify the assertion of 
the engineer sending them, that they are good for 10 years more. 



88 CONSTRUCTION AND MAINTENANCE OF ROADS. 

The following extract, from the " Railroad Gazette," is also corrob- 
orative : 

The German Railroad Union some time ago made inquiries as to the 
extent to which processes for preserving ties were employed, and what the 
results were. 

It appears from statistics of German railroads which have used treated 
ties more or less since 1840, and therefore have had time to test thorough- 
ly the life of the ties, that the average life of ties not treated, and of those 
treated with chloride of zinc or creosote has been : 

Not treated. Treated. 

Oak ties 13.6 years. 19.5 years. 

Firties .' 7.2 •' ' 14 to 16 

Pine ties 5.0 " 8 to 10 " 

Beech ties 3.0 " 15 to 18 " 

The average life of 831,341 pine ties treated in various ways on thirteen 
German roads was 14 years. 

It follows from this that there is an increase in the life of ties treated 
with chloride of zinc or creosote, amounting to about 40 per cent, for oak, 
100 to 130 per cent, for fir, 60 to 100 per cent, for pine, and 400 to 500 per 
cent, for beech. 

It thus appears that there is a great deal gained with any kind of 
wood, but most with some of those usually not considered good for 
ties, fir and beech being made almost as durable as oak. Bischoff says 
that it is of little advantage to secure the ties from decay for longer periods 
than above stated, as the ties usually become worn out or crushed by that 
time, even if not decayed. 

Commenting on these facts, Bischoff says that it is now generally ad- 
mitted that the choice lies between creosote and chloride of zinc ; that 
creosote is the best antiseptic material, but also that it is the dearest. 

There can be but little doubt that the antiseptic properties of the 
creosoting process are of more value than the increased life it would give 
lo the blocks. 

On account of the absence of proper stone and the cheapness of wood 
in large areas of our country, the small first cost of wood pavements seems 
to make it worth while to give them an intelligent trial. 

The thoroughness with which wood pavements can be cleansed de- 
pends on the size of the joints and the firmness of their filling. The 
practice in London, when the mud is at all sticky and not so thick as to 
require scraping, is to water and then sweep with a revolving broom, the 
thoroughness of the cleansing being almost directly as the amount of 
water. In hot w^eather a disinfectant is sometimes applied after sweep- 
ing. 

ASPHALTE AND BiTUMEN. 

Dictionary and encyclopedia makers, as well as chemists, seem to use 
these terms interchangeably. M. Leon Mab, in his " Guide Pratique 
pour La Fabrication et L' Application de L' Aspkalte et des BitumeSy* 



CONSTRUCTION AND MAINTENANCE OF ROADS. 89 

after speaking of the lack of definition in the two terms as generally used, 
gives the following, viz. : 

'' Asphalte, Bituminous Limestone." 

" Bitiunen, The black and viscid substance which we find disseminated 
in the pores of bituminous limestone and in the interstices of the molasses 
of Seyssel or the sands of Auvergne." 

'' Asphaltic Mastic, Bituminous limestone transformed by dressing 
{cuissoti) and by the addition of a small quantity of bitumen." 

He adds : " We employ these definitions throughout this work, and 
give to them the senses which we have just indicated, and I hope strong- 
ly that they will be adopted for use, for they seem to be the most reason- 
able." 

It is believed his definitions have been generally accepted by European 
technical writers and in specifications relating to the use of these mate- 
rials,* and the writer in this paper will use them as above defined, except- 
ing that the bitumens from Trinidad and Cuba will be included with those 
mentioned by M Malo. 

In view of the practice in this country two other definitions seem neces- 
sary, viz.: 

Bituminous mastics, mixtures of bitumen, either having an earthy 
gangite, like those of Trinidad and Cuba, or purer ones, like Graharaite 
and Albertite, with limestone or other substances not naturally impreg- 
nated, which add to its resistance to wear, and — 

Tar Mastic, a mixture in which the bitumen is replaced by (usually) 
gas tar. 

M. Malo further characterizes asphalte as a carbonate of lime perfectly 
pure (excepting, sometimes, a trace of silica), naturally impregnated with 
bitumen. Its characteristic color is that of chocolate — which it also resem- 
bles in fracture — mean specific gra\ity 2.235. It is quite hard when cold, 
and falls to pieces at a heat of about 122 deg.-i4o deg. F. At an interme- 
diate temperature it flattens under the blows of a hammer ; its structure 
vanes with its locality, but in general should be fine-grained and homoge- 
neous, without particles of unimpregnated stone. 

In the poorer qualities the impregnation, though regular, does not ex- 
ceed 6 per cent., or the bitumen is injected into minute cracks, showing 
under the microscope that the impregnation is not molecular, or the rock 
contains clay, or, as in the case of Lobsan, the bitumen contains light oils 
which injure the consistence of the mastic, in which case the light oils are 
driven off by heat, the remainder being used. 

Generally, we may say that the more uniform and microscopic the 
impregnation of the lime is, and freer from extraneous matters, the better 
it is. 

*In Paris, the asphalted sidewalks are universally spoken of as bitumen, in distinction from 
■wheel ways, which are called asphalte. 



90 CONSTRUCTION AND MAINTENANCE OF ROADS. 

Neglecting the Tubal Cain stage of its history, asphalle was first ap- 
plied to sidewalks and wheelways as a mastic, but in that state was not 
sufficiently resistant for streets of much traffic. It was seen, however, 
that in summer the pieces of rock that fell from the carts between the 
mine and the mastic works at Seyssel compressed under the wheels. In 
1849, a Swiss Engmeer, M. Merian, put this lesson to profit, by construct- 
ing a Macadam road of asphalte, which was compacted with a roller. In 
spite of the instability of its foundation and the irregularity of its mainte- 
nance, this road is still in very good order. (Malo, p. 108.) 
Compressed Asphalte. 

The first compressed asphalte was laid in Paris by M. Vaudry in 1854, 
though it was not till 1858 that it was laid on a large scale; the area 
covered in 1878 by pavements and cross-walks was 324,654 square yards, 
or nearly 14 miles of a street with a 40-foot wheelway. The earlier prac- 
tice was to " decrepitate " the rock (broken to about the proper size for 
Macadam) by heating it to about 140 degs. F. in sha low iron pans. Skill 
was necessary in this operation, as the rock was liable to be burned, /. e., 
have too m_uch of the bitumen driven off, or to have too little, and some- 
times both results were reached in the same batch. The walks in Union 
Square, N. Y., are an example ot the ill effects of unskillful decrepitation. 

The rock was also broken up by the direct action of steam, but it was 
impossible to secure a product of uniform fineness, and difficult to remove 
all the moisture. After experiments with various machines, a Blake 
crusher is first used, the pieces are then passed through a Carr's disinte- 
grator, after w^hich the powdered rock is heated in revolving cylinders to 
from 212 degs. to 284 degs. F. (depending partly on the distance it has to 
be carried), and transported to the place where it is to be laid, usually in 
covered sheet-iron wagons. 

The permanence of this pavement depends primarily on the stability 
of its foundation, which is usually of concrete (though old asphalte is 
sometimes used) 6 inches thick ; on this, when it is thoroughly dried, 
the heated powder is spread, by means of rakes, to such thickness that 
when compressed it shall be from 1% to 2% inches thick — depending on 
the probable amount of traffic. The compression, which is termed pilon- 
nage, is effected by the aid of the tools figured. The fouloir is first used 
along the junction of the asphalte with either the curb-stone or the paved 
gutters, while the rest of the surface is compacted by the pilon, beginning 
with light blows and ending with vigorous ones. All these tools are 
heated nearly red hot, as the powder sticks to them when they are cold. 
After the surface has been thoroughly compacted it is tested with a 
straight-edge, and then rubbed with the lissoir, also heated, giving a glaze 
to the surface, after which it is dusted over with cement and allowed to 
cool thoroughly before the traffic is turned on it. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 91 

Efforts have been made to secure a more regular surface than is prac- 
ticable by pilonnage and at less expense by rolling, but it was difficult to 
so heat the rollers that the powder would not adhere, and the pavement 
was liable to tear as it was about finished. 

The powder retains heat for some time, and the work goes on in a 
continuous sheet for the day, a gang of ten or twelve men being able to 
complete about 600 square yards per day. In the morning the uncom- 
pressed powder at the edge of the work of the day before is swept away, 
and hot powder put in its place, which in turn is removed after having 
heated the old work ; the spreading and pilonnage then goes oaas before, 
leaving small or no trace of the junction. 

Great care should be taken that the concrete foundation is thoroughly 
dry, otherwise the hot powder evolves steam, which permeates the powder 

Foulolr Pii°^- 




and leaves the compressed mass in nodules called almonds. These do not 
show during pilonnage, but are developed by the traffic, when the place is 
cut out and refilled. A very slight defect seems capable of starling a hole 
in compressed asphalte, and for the first two weeks it is under traffic it 
should be watched closely and repaired promptly. The defects caused by 
deficient aggregation of the molecules show themselves more readily than 
those caused by steam. Overheating, which renders the asphalte as inert 
as sand, is one cause of deficient aggregation, and laying the powder too 
cold IS another. 

When the asphalte is too rich in bitumen or the bitumen is too oily, 
the compressed asphalte forms waves under the traffic, sometimes longi- 
tudinal and at others transverse. 

So far but few asphaltes have been found that are available for com- 
pressed pavements. The Val de Travers (from Neuchatel) was first used. 



92 CONSTRUCTION AND MAINTENANCE OF ROADS. . 

but in 1867 Seyssel (Pyrimont) was used with success in the Rue de 
Richelieu, and both have since been used by the General Asphalte Com- 
pany of Paris, which, until January, 1878, laid and maintained the asphalte 
roads in that city. The Val de Travers asphalte is of the two more reg- 
ular in its grain and impregnation, and richer in bit«amen, having 9 to 13 
per cent. Seyssel is not so regular in its grain and impregnation, and 
contains from 7j^ to 10 per cent, of bitumen. The base of both is equally 
pure carbonate of lime, containing about 2 per cent, as a maximum of 
silica. Of the two, M. Ernest Chabrier, for a long time manager of the 
Paris Company, in his paper read before the Institute of Civil Engineers,, 
says : " No engineer could conscientiously say that the Val de Travers is 
better than the Seyssel asphalte. The former may be safer in the execu- 
tion of a work not subjected to supervision ; the latter offers greater guar- 
antees of good execution, because more care is required in the work." 

It was also held that, for compression at least, the two should not be 
mixed, and that only pure limestone, impregnated with from 8 to 12 per 
cent, of bitumen, was available for compression ; but within the last two 
or three years the Limmer & Vorwohle Asphalte Company of London 
found their mastic pavement breaking up and employed the .Sicihan 
arphalte (which is certified by W. J. Fewtrell, F. R. S., to contain as 
high as 30 per cent, of bitumen) in compressed pavements and sidewalks. 
Aldgate and Newgate streets having been laid with this asphalte are 
apparently wearing well. And in Paris, Paul Crochet, who has the 
contract for new work and maintenance for five years from 1878 (see 
Appendix, No. 4) has used, so far, a mixture of Lobsan and Seyssel 
Forens-Nord. M. Malo says of Lobsan : " It contains within its bitumen 
an oily substance which renders it too soft and injurious to the consist- 
ence of asphaltic mastic ; we free it from this oil by distillation, after ^ 
which it is in a proper state to be used." The Seyssel Forens is a heavy 
limestone, very poor in bitumen. As after a careful i»xVestigation the 
engineers of the Ponts et Chaussees have allowed it to be used in Paris- 
it seems that, theoretically, at least, a mixture of two dissimilar asphaltes 
is not disadvantageous, nor is the use of an asphalte that contains a hydro- 
carbon of the more volatile series ; also that, as in the case of the Sicilian,, 
an asphalte containing more than twice as much bitumen as was formerly 
thought the safe maximum can be successfully laid under exceptionally 
heavy traffic. 

There was an unwillingness on the part of the manager of the Limmer 
& Vorwohle Company to explain the manner in which he handled his 
material, but it is probable that it was skillfully roasted so as to drive off 
the excess of bitumen as his compressed roadways showed less tendency 
to roll in hot weather than those laid from Val de Travers rock. 

By the kindness of Count Kielmansegge, one of the directors of the 



CONSTRUCTION AND MAINTENANCE OF ROADS, 93 

Neuchatel Company, I am able to give the following analyses of Val de 
Travers asphalte. These two sets of analyses by Charles Heisch, F. C. S., 
were made in consequence of complaints by their customers that the 
rock was becoming too rich in bitumen : 

September, 1876. 5 samples. 





9.46 


9.48 11.98 
90.52 88.02 


11.96 

88.04 


10.06 


Carbonate of lime 


90.54 


89.94 








Loss at 212° 


100.00 
1.46 


100.00 100.00 
1.42 3.04 

. 3 samples. 
10.2 


100.00 
3.22 

11.5 

88.5 

100.0 
2.6 


100.00 
1.92 


Bitumen 


July, 1877 


12.32 


Carbonate of lime 




89.8 

100.0 
2.46 


t7.68 


Loss at 212° 


100.00 
3.2 



The loss was moisture and light oils. A small amount of silica was 
estimated with the lime. 

Mr. J. Knight, Secretary Society Francais des Asphaltes, gave me the 
following analyses made by Steen, of Copenhagen : 

rorcrnnir .0 no J Soluble in ether 9.62 

a. oo.i P jr^^r.. jUigamc 1^-""| Insoluble in ether.. . . 2.35 

Seyssel Pyrxmont ^ 33^,, j Soluble in acid 86.45 

» "'( Insoluble in acid 1.55 

'organic g.Ool?"^'^?'^^.^*^!!; ^ -f^ 

a«™=«i r<o-^^ K^,-a v^io""'^ "^-""l Insoluble in ether 55 

Seyssel Garde bois j^^^^^^j, 90 30 /Soluble in acid 85.10 

[^moiganii ^"•■^'^\lnsolubleinacid 5.20 

The Garde bois asphalte is only used as a mastic, according to Mr. 
Knight, not having coherence enough for satisfactory compression. 

Mr. W. H. Delano, manager of the Compagnie Generaledes Asphaltes 
de France, says of an asphalte for compression that " it should be carbon- 
ate of lime (without admixture of foreign material) and mineral bitumen 
which does not evaporate at 302 degs. F. Some bitumens contain an oil 
which commences to evaporate at 158 degs. F.; they may, when purged of 
the light oil, leave an excellent quality behind. The physical qualities of 
the limestone should also be carefully examined ; but whatever the result 
of even a careful analysis may be, the value of a new asphalte cannot safe- 
ly be determined except by actual experience extending over three years, 
at least, of hard winters and hot summers." Col. Haywood also was un- 
derstood to say that at least three years were necessary to prove the good 
qualities of a new or untried asphalte. His experience is strongly against 
any form of asphalte pavement except " compressed." 

From a sanitary point of view an asphalte pavement is without a 
peer ; its surface is smooth, regular and non-absorbent, with no cavities or 
cracks of any kind to retain the infected mud and dust of the streets, and 
the soil beneath it is kept dry. It is more thoroughly cleaned, either by 
sweeping or washing, than any other pavement. Its freedom from noise 
and other excellencies is fast placing it in all the business and banking 



94 CONSTRUCTION AND MAINTENANCE OF ROADS. 

streets of the City of London, where it seems to be superseding all other 
pavements. 

In comparison with granite pavements, its great economy is to brain 
workers and the owners of horses. M. Darcy estimates that the expense 
of maintaining and renewing horses and carriages in Paris would be re- 
duced one-half if asphalte w^as substituted for pavement throughout the city. 

Its disadvantages are, it is expensive ; it is not well to lay it on a grade 
much greater than two per cent.; it is subject to slight decay in the gut-- 
ters, which they try to correct in Paris by laying the gutters with stone 
sets ; and lastly, the most serious charge, that it is shppery and dangerous 
to horses. No doubt at the commencement of a rain, or in foggy weather, 
its surface is slippery unless it is very clean, and a horse turned suddenly 
is liable to fall ; but when dry or thoroughly wet no such charge can be 
brought against it. 

Referring to Col. Haywood's much quoted tables comparing granite^ 
asphalte, and wood,we find that before an accident occurs a London horse 
will travel on granite 132, on asphalte 191, and on wood 446 miles* 
" That of those accidents which are most obstructive to the traffic, as well as 
most injurious to the horses, asphalte had the greater proportion, granite 
the next and wood the least." 

He says further in a report upon asphalte and wood pavements : 

First. — As regards convenience : That asphalte is the smoothest,, 
driest, cleanest, most pleasing to the eye and the most agreeable pave- 
ment for general purposes, but wood is the most quiet. 

Second. — As regards cleansing : That wood may be kept cleaner than 
it hitherto has been, but will be more difficult to cleanse effectually than 
asphalte. That as both pavements require occasionally strewing with 
sand or gravel, there is no difference between them in that respect. 

Third. — As regards construction and repairs : That asphalte and 
wood, taking all seasons into account, can be laid and repaired with about 
equal facility ; but the smallest, neatest, cleanest and most durable repairs 
can be made in asphalte. 

Fourth. — As regards safety : That, whether considered in reference 
to the distance that a horse may travel before it meets with an accident, or 
the nature of the accident, or the facility with which a horse can recover 
its footing, or the speed at which it is safe to travel, or the gradient at 
which the material can be laid, wood is superior to asphalte. 

Fifth. — As regards durability and cost : That wood pavements, with 
repairs, have, in this city, had a life varying from six to nineteen years, 
and that, with repairs, an average life of about ten years may be obtained ; 
that the durability of the asphaltes is not known, but that under the sys- 
tem of maintenance adopted they may last as long as wood ; that, con- 
trasting the tenders for laying and maintaining for a term of years the two 
best pavements of their kinds, wood will be the dearest. 

The above remarks refer to London, and inasmuch as our climate is 
much the driest, and as asphalte is safer where dry, the comparison would be 
more in favor of asphalte here than there. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 95 

Both the compressed and mastic surfaces are easily and thoroughly 
cleaned by washing and by sweeping when either wet or dry. A squeegee, 
which is a long-handled scraper with a rubber blade 32 inches long, when 
pushed along a wet pavement both cleans and dries it. 

It may at first sight seem that if a person will indulge in the luxury 
of changing his gas company on the recipt of each bill he should be com- 
pelled to make good the surface of the street, and the ease or difficulty of 
making repairs should largely be a consideration for those who open the 
streets, but as a matter of fact it is almost impossible to properly inspect 
the work of plumbers, and while one avenue in this city has on its surface 
a double-tracked horse railroad and 240 elevated railroad columns per 
mile, with one sewer, three water pipes, and eight gas pipes (belonging to 
four different companies) under it, the subject cannot be without interest. 
In general, any pavement with a foundation of concrete can be, and prob- 
ably will be, more thoroughly repaired than one with a loose foundation, 
such as sand, broken stones, or Telford. For the surface, asphalte is su- 
perior to all others in the matter of neatness. Macadam next, and tne 
granite and wood pavements next. 

AsPHALTic Mastic. 

The asphaltic mastic, which is greatly used in Paris for sidewalks, ib 
made, as above defined, from asphalte and bitumen. This bitumen vv'as 
at first obtained from the asphalte and molasses of Seyssel by boiling either 
the broken stone or sand (of the molasses) when the bitumen separated, 
and was skimmed off the surface of the water and sides of the boiler. This 
bitumen (after being re-melted and allowed to settle to clear it from sand, 
if necessary) is melted in an iron boiler to the amount of between 5 and 10 
per cent, of the required batch, and the powdered asphalte added slowly 
and stirred in until all is thoroughly incorporated. It is then cast in molds 
for sale or use as mastic. When this mastic is used it is necessary to break 
it up and add it again to melted bitumen, after which 50 to 60 per cent, of 
fine or coarse silicious sand is added, and the whole kept heated till it does 
not stick to a clean wooden stirrer. 

The mastic is then taken to the place where it is to be laid, in a locomo- 
bile, essentially a horizontal cylinder on four wheels, with a fire-box under 
it and an arrangement for stirring the mastic so as thoroughly to mix the 
gravel and to keep the mixture from burning. It is then laid on a concrete 
foundation, generally for sidewalks Yz inch thick, or more. It is poured 
on the concrete from conical sheet-iron pails, and spread by the aid of a 
wooden hand float. After the spreading is completed, sand, and in some 
instances gravel the size of peas, is added, and the surface well rubbed. 
The sand adds to the wear of the sidewalk, and prevents the mastic 
softening under the heat of the sun. The mastic is sometimes laid in one 
course and sometimes in two. 



96 CONSTRUCTION AND MAINTENANCE OF ROADS. 

M. Malo insists on the bitumen used for mastic being the same as that 
impregnating the hmestone, but, on account of its scarcity, it has been al- 
most entirely replaced by refined and tempered Trinidad or other bitu- 
men. 

Crude Trinidad contains, besides water, chips, leaves, etc., twenty- 
five to thirty per cent, of clay, in which state it is brittle, and the clay, as 
in the case of compressed asphalte, is an element of weakness, as it at- 
tracts water. It is refined, according to Malo, '' with goudron," a product 
of a second distillation of schists, which, at a temperature of 59 degrees to 
68 degrees Fahrenheit, has the aspect of a completely liquid bitumen ; 600 
to 700 pounds of this goudron is boiled in a chaldron, in^o which the 
crude bitumen, broken to the size of an ^'g%, is thrown in successive doses 
until the weight is 1,700 to 1,900 pounds. After the ebullition has ceased 
the fire is drawn and time allowed for the sand and earth to settle, when 
the purified bitumen is drawn off and strained. The mineral tar of 
Autun is said to be the best substance now in the market for refining and 
tempering bitumen. 

M. Malo deprecates the use of oils from boghead coal and petroleums 
generally. All of the manufacturers interviewed on the subject denied the 
use of still bottoms or petroleums, and most agreed with Malo that bog- 
head oils should not be used, on account of the cracks which occurred in 
the mastic ; others claimed that the cracks were due either to a poorer 
quality of asphalte than they used, or to an insufficient purification of the 
Trinidad. See also App. No. 4, art. 17, and App. No. 5, art. 21. 

There is a great difference between the true asphaltic mastics, depend- 
ing on the purity and quality of the asphalte, the purity and component 
parts of the goudron, and the skill of manipulation. A well-made mastic 
IS decidedly harder than compressed asphalte, which to a certain extent is 
partially fluid under pressure, and increases in density under traffic much 
faster than the surface is abraded. Mastic, on the other hand, as above 
stated, is hard, crumbling under too great pressure, not noticeably com- 
pressible, but disintegrating under the blows of horses' feet. It, however, 
has much more cohesion than compressed asphalte, and should be pre- 
ferred in those situations where it is not liable to receive the compressive 
action of heavy loads, and is exposed in large areas to changes of tem- 
perature ; the partial fluidity of asphalte keeps such cracks closed under 
traffic. 

In the courts of the new House of ParUament. eighty by forty-six feet, 
Claridge's mastic stands without cracks, a beautiful surface ; while care- 
fully laid compressed asphalte in the court next to it has cracks in its sur- 
face. Claridge's asphaltic mastic, which has a very high reputation in 
London, is made from Seyssel asphalte and a very carefully refined Trini- 
dad goudron. It is claimed that the Trinidad bitumen, when thoroughly 



CONSTRUCTION AND MAINTENANCE OF ROADS. 97 

cleared of its clay, has the greatest cohesive strength of any of the bitu- 
mens, and the Claridge Company claim that they conduct their refining 
processes with more skill and thoroughness than any other company. 
Their mastic is laid in two courses in strips about 3 feet wide, breaking 
joints. 

It is believed that in Paris no compressed asphalte is laid for side- 
walks, but in London the Limmer Company is compressing Sicilian on 
sidewalks, and the Val de Travers Company always use compressed. 

Some mastic was laid in London streets, but it is now being rapidly 
repaired or renewed with compressed asphalte, except in narrow streets 
of small traffic, nor is asphaltic mastic laid in the wheelways of Paris. 

There is one theoretical point in regard to different asphaltes to which 
the attention of the Society may be called. That is the fact that some 
asphaltes will compress and others will only make mastics. The Val de 
Travers and the Seyssel are very good for either purpose. Lobsan is 
capable of being compressed, and with proper treatment, making a mastic. 
Sicilian, as far as known, has only been employed for compression. The 
asphaltes of Hanover and Brunswick, while they make very good mastics, 
seem incapable, with the present knowledge, of being compressed, and 
the writer has met no one who could explain the cause of the differences. 
It evidently does not lie in the quantity of bitumen contained in the rock, 
as some Hanover asphaltes contain more than either the Seyssel or the 
Val de Travers. 

Bituminous Mastic. 

Bituminous mastics, or the fictitious mastics of Malo and the French 
writers, were experimented with very generally in Europe, in the hope of 
findmg something as useful as asphalte at a less price ; but it was found 
that no practicable degree of heat and pressure would give the microscopic 
impregnation of grain found in the natural mineral. 

In this country the effort took a different direction. Refined and prop- 
erly tempered Trinidad bitumen was mixed with limestone or fine or coarse 
sand, and a product was sought between asphalte and asphaltic mastic. 
It is applied neither as a dry powder nor in a fluid or semi-fluid condition, 
but as a sticky and coherent mass, and is subjected to pilonnage and roll- 
ing. While it does not seem to have either the ductiUty under traffic or 
the resistance to wear of asphalte, it has less hard brittleness than the 
true asphaltic mastic ; its great difficulty being a tendency to disintegrate 
in a rotten manner, possibly from the use of improper oil in refining and 
tempering the Trinidad bitumen, or else from the inherent difficulty of 
making an artificial mixture equal in quality to the natural product. 

The most successful pavement- of this class in this city is the block on 
Fifth avenue opposite the Worth Monument, laid by the " Grahamite 
Company." Its component parts are understood to have been a mixture 



98 CONSTRUCTION AND MAINTENANCE OF ROADS, 

of Trinidad bitumen with fine sea sand containing a little carbonate of 
lime, and enough Grahamite or Ritchie mineral ♦' to save the patent." 
This pavement was laid in the spring of 1873, ^rid after the rectification 
of surface generally necessary, it stood till the fall of '7? without requir- 
ing any repairs that could be charged to its own weakness. It was re- 
paired by another company in the fall of 1878, and now requires addi- 
tional attention. During this time it has filled all the conditions demanded 
of a good pavement to a greater extent than any other pavement in the 
city. Three other pieces laid by this company have not proved so suc- 
cessful. 

Pavements of this class are very fully described in General Gilmore's 
Roads, Streets and Pavements. 

They are being extensively laid in Washington under a contract for 
three years' maintenance. As in France and England, it is held that 
whatever the physical properties and composition of an untried asphalte 
may be, it is not safe to pronounce it a success until after three years' 
wear ; it seems that a longer maintenance contract would be advisable. 

In London, Colonel Haywood, as noticed under the head of Wood 
Pavements, lets his asphalte pavements at a certain price per square yard 
for laying, and a provision that they shall be maintained for 2 years at 
the contractor's expense and 1 5 years at an agreed price per square yard 
per annum, and a good pavement be given to the city at the end of the 
17 years. 

Several different kinds of pavements, compressed and fictitious and 
other mastics, were laid, the Val de Travers compressed asphalte being 
the only one that was satisfactory, and most of the other pavements were 
relaid by that company at the expense of the sureties. The Limmer & 
Vorwohle Company, however, introduced the use of Sicilian, with which 
they have relaid Newgate and Aldgate streets, and are relaying Cornhill. • 

In the City of Jassy, Roumania, the contract (see Appendix No. 5) is 
based on the London plan. The work was commenced in 1873 and fin- 
ished in 1878. It is to be maintained at the contractor's expense until 
1880, from that time, and until 1895, at a stipulated price. 

In Paris (see Appendix No. 4) the system is to let the construction, 
maintenance, and repairs of pavements and footpaths for a term of years, 
5 to 10, without guarantee of wear, relying on rigorous specifications and 
thorough inspection for the excellence of the work. 

The plan pursued in London and Jassy seems preferable, even with the 
natural asphaltes, for after the solidity of the foundation is assured, the 
duration of the wheelway depends so much on the technical skill and 
thorough honesty exhibited in small details, that the burden of proper 
inspection should be thrown on the contractor by his having a large 
pecuniary interest in the soundness of the work done and material fur- 



CONSTRUCTION AND MAINTENANCE OF ROADS. 99 

nished. The inspection, however, should be close enough to keep the 
engineer in charge fully informed of the methods and materials em- 
ployed, particularly towards the close of the contract. But no greater 
injury could be done to a city's system of streets than strictly enforcing 
the specifications of some of the 300 and more patents taken out for 
mastic pavements. 

The possibility of having any street in continuous good order for 17 
years is probably too much for the imagination of the average New 
Yorker. And no one can well realize the effects of having all the streets 
so kept in repair. 

Tar Mastic. 

Among the legacies of the " ring" were the various tar pavements. 
They were worse than the wood pavements, though not being so thick, 
they have not proved so enduring a nuisance as the latter. 

The best of them are understood to have been made of crude coal tar 
mixed with gravel and sand, and on the evaporation of the light oils they 
went to pieces, generally with great celerity. Occasionally a patch would 
be found that stood the traffic pretty well ; this was supposed to result 
from the evaporation of the oils before mixing with the gravel. G. 
Leverich, Member of the Society, proposed to secure a uniform product 
by passing steam of a certain temperature through the tar and driving off 
all the oils of low specific gravity. Coal tar is now generally reduced to 
pitch to get the aniline colors, their most valuable product, and the pitch 
may be tempered by melting with dead oils, a waste product of the dis- 
tillation. It, however, is very brittle, and it is doubtful if it can be em- 
ployed economically, except for side- walks of light traffic. 



loo CONSTRUCTION AND MAINTENANCE OF ROADS. 



APPENDIX NO. I. 

Extract from Specification of W. S. Till, Borough Surveyor, Birmingham, 1877. 

The whole of the carriage way to be excavated to the required depth, and the foundations 
-formed to uniform gradients and proper cross sections, with ashes or other approved materials. 
When these have been rolled and are well set, the contractor to coat the whole width and length 
of the carriage way with not less than 8 inches of good, strong, clean gravel, screened through a 
|-inch riddle, or with not less than 8 inches of approved slag, broken regularly to such a size that 
the largest piece, on its greatest dimension, will pass through a 3-inch ring. 

The gravel or slag to be well gritted and watered, and kept raked togethei and rolled until 
the whole is consolidated. ********* 

The contractor to coat the carriage way, throughout its whole length and width, with not less 
than 6 inches of Eowley Eagstone, broken to pass through a 2i-inch ring. 

The stone to be gritted, watered, and kept together, raked and rolled until the whole is con- 
solidated. Crown 6 inches above curbstone. Each layer to be laid on complete throughout the 
whole length and width of carriage way, and each layer to be separately rolled with a heavy 
roller. 

APPENDIX NO. 2. 

Extract from Specification for Telford, Macadam and Trap Block Gutters on 

Fifth Avenue. 

(4). Description of Materials. — The stone blocks are to be of double and uniform quahty, 
each measuring, on the face or upper surface, not less than 4 nor more than 8 inches in length, 
and not less than 4 nor more than 6 inches in width, and in depth not less than 6 nor more than 8 
inches ; blocks of 4 inches in width on the'r face to be not less than 3 inches in width at the base; 
all other blocks on transverse measurement on the base, to be not more than 2 inches less 
than on the face, but no block on the base shall be of less width or length than 3 inches, and to 
be in all respects equal to the specimen blocks at the office of the Commissioner of Public 
"Works. 

It is also required that the sides of the stones (which form the joints) shall be so sufficiently 
even and properly shaped that joints may be formed with a similar side not exceeding f of an 
inch, no stone having an objectionable protruding face will be accepted or allowed to be used for 
paving. They will be carefully inspected after they are brought on the line of the Avork, and all 
blocks which, in quality and dimensions, do not conform strictly to these specifications, will be 
rejected, and must be immediately removed from the line of the work. The contractor will be 
required to furnish such laborers as may be necessary to aid the inspector in the examination 
and culling of the blocks ; and in case the contractor shall neglect or refuse so to do. such labor- 
•eis as in the opinion of the Commissioner of Public Works may be necessary, will be employed 
by the said Commissioner, and the expense thus incurred by him will be deducted and paid out 
of any money then due or which may hereafter grow due to the said contractor under this agree- 
ment. The blocks must be of trap rock or of syenite, equal in hardness to what is called Quincy 
granite. 

Telford. — The stone for the foundation of the pavement Is to be sound, hard and durable 
quarry stone, each from eight to ten inches in depth, from three to six inches in width, and from 
six to fourteen inches in length, and of a sufficiently uniform size to be acceptable ; except the 
stone under the gutters, which only differ from those above described in that they must be not 
less than six inches in depth, and except the course of stone under the Macadam, which is next 
to the gutters or the bridge stone, which stone is to be twelve inches in depth, and in every 
other respect as first above described. 



CONSTRUCTION AND MAINTENANCE OF ROADS. loi 

The broken stone for the bottom course is to be of trap rock, and of such size that would 
pass in any direction through a ring with interior diameter of 2^ inches, and of a sufficiently uni- 
form size and proper shape to be acceptable, to be composed only of stone that is hard and 
durable, and sufficiently free from screenings, and practically free from dirt and other foreign 
matter. The broken stone composing the next overlying course is to be the same in every respect 
as just described, except that each stone is to be of such size that would pass in any direction 
through a ring with interior diameter of 2 inches. 

The coarse screenings are to be those of trap rock ; the stone is to be practically fi-ee from 
dirt and other foreign matter, to be composed of material only that is hard and durable, no particle 
of which is to be of larger size in any direction than \\ inches, and all the particles to be of such 
relative size to \\ inches as shall be acceptable; through these screenings is to be evenly mLxed 
before rolling a sufficient quantity of the finer screenings of trap rock to form a proper and secure 
bond. 

The fine screenings of trap rock are to be practically free from dirt and other foreign matter, 
and to be composed of material both as to size and quality that will be acceptable. 

(9). Prepaeation of Egad Bed, &c. — All paving and other stones necessary to be removed 
shall be taken up and immediately removed from the line of the work ; the Belgian and granite 
blocks to be deposited where directed by the "Water Purveyor for the use of the city; the subsoil 
or other matter (be it earth, rock or other material) shall then be excavated and removed, to such 
depth to be determined by the engineer in charge, that when rolled and finished, irrespective of 
the covering of fine screenings, the pavement throughout its entire extent shall be at least 
sixteen inches thick. Should there be any spongy material or vegetable matter in the bed thus 
prepared, all such material shall be removed, and the space filled with clean gravel or sand care- 
fully rammed or rolled, so as to make such filling compact and solid. No ploughing will be 
allowed in preparing the foundation. 

The road bed shall be truly shaped and trimmed to the required grade, and with sucli crovsm 
as shall be directed by the said engineer, and rolled with a roller weighing not less than two tons, 
until the surface is firm and compact. 

Laying the Foundation or Pavement. — After the road bed is prepared, agreeably to the 
terms of this specification and to the satisfaction of the engineer, and the stone hauled and de- 
posited thereon, the foundation stones shall be laid by hand in the form of a close, firm pavement, 
They shall be set on thoir broadest edges and lengthwise across the road, except in the case 
of the stone under the Macadam, which is next the gutter stones or bridge stones, which 
foundation stone is to be placed with its longest side pai-allel to the curb or bridge stone^ 
after being set closely together, they are to be firmly wedged by inserting and driving down 
with a bar, in all possible places between them, stones, as near as pi-acticable, of the same 
depth, until all the stones are bound and clamped in proper position; all the projections and 
Irregularities of the upper part of the pavement shall then be broken off with a hammer, care 
being taken not to loosen the pavement, and the spalls and chips are to be worked and 
driven with the hammer into all the interstices not already filled by the process of wedging, so 
that the pavement, when completed, shall present a sufficiently even surface, and be at each 
point of such thickness as required by these specifications. No wedging shall be done within 
twenty-five feet of the face of the work that is being laid, and the stone foundation must be in 
a compact and satisfactory condition in every respect at the time of the spreading of the broken 
stone. 

Macadamizing. — After the stone foundation has been completed agreeably to these speci- 
fications, and has passed the inspection of the said engineer, a layer of broken stone of the quality 
and size herein specified for the bottom course, and of such a depth as will make 4 inches when 
rolled, shall be spread evenly over the pavement ; this layer is then to be rolled until sufficiently 
compact. 

The next overlying course will be of stone, as hereinbefore described for said course, and is to 
be spread so that the surface will be uniformly 1 inch below the grade and crown when the pave- 
ment is finished. 

Stone hammers are to be used on this course, so that when rolled as much as shall be re- 
quired the surface of each stone that is exposed will not have a longer dimension in any direction 
than 1 inch. 



I02 CONSTRUCTION AND MAINTENANCE OF ROADS. 

A layer consisting of the coarse screenings herein specified is then to be applied and spread to 
such depth as will bring the surface to the proper grade, irrespective of the finish of fine screen- 
ings; this layer is then to be rolled, and during the progress of the rolling, if necessary, coarse 
screenings shall from time to time be applied, so that when the rolling ceases the roadway is truly 
surfaced to the required grade and crown. This layer is to be rolled until all settlement ceases and 
the stones are thoi-oughly compact and the surface true to the grade and crown. 

During the process of rolling any course of stone there shall, when required, be spread 
lightly over the same from a shovel, the fine screenings of trap rock herein described ; and after 
the upper layer has become thoroughly compact, there shall be spread upon the surface fine 
screenings, so much as to produce a covering half an inch in depth when rolled, and the rolling 
is to continue until, by a sufficient use of water, a wave is produced before the wheel of the 
roller. 

The.rolling of the Macadam stone and screenings shall be done with a roller weighing not less 
than any of the steam rollers in the possession of the Department of Public Works. 

Each layer of broken stone and the screenings or binding material shall be well and 
thoroughly rolled, and the rolling upon each layer shall be prosecuted until, in the opinion of 
the engineer, each course shall have been completed, as hereinbefore specified, and until each 
layer and the finished surface shall be rolled and finished to his entire satisfaction and approval. 

"While the rolling of each layer of broken stone and the screenings or binding material is 
being prosecuted the work shall be kept moistened to such extent and in such manner as re- 
quired, and care shall be taken that too much water is not applied while rolling the first layer, 
and until after the interstices are well filled with the binding material. 

The pavement, when completed, shall be at each point of such construction and at least of 
such a depth as required by the specifications, and of such crown and such form of gutter as 
shall be directed, and in any case the thickness of the pavement is to be determined on a line at 
right angles to the grade and crown. 

The use of a proper roller, rammers, or other suitable implement, is to be substituted for 
that of the steam-roller when necessary. 

The construction of the foundation stones, and the Macadam pavement shall proceed so as to 
be practically equally as far advanced across the entire width of said pavements. 

Particular care and attention will be required in obtaining a satisfactory joining of the Ma- 
cadam paving and the blocks in the gutters. 

Paving the Gutters. — Upon the stone foundation already described, shall be laid a bed of 
clean, sharp sand, not too fine, or clean fine gravtl, of the depth necessary (about 4 inches) to 
bring the paving to the proper shape and grade when rammed. The stone blocks are to be laid 
with joints at right angles to the curb, with joints not exceeding three-quarters of an inch, at 
such grade and in such form as shall be directed ; each course of blocks shall be of a uniform 
width and depth, and so laid that all longitudinal joints shall be broken by a lap of at least one 
inch ; and the blocks next the curb shall break joints with the curb by at least one inch ; as the 
blocks are laid the joints shall be so filled with sand or gravel as to secure, when the work herein 
mentioned is completed, against there being any spaces not filled with sand or gravel between 
the blocks ; they shall be covered with clean, sharp sand, which shall be raked until the joints 
"become filled therewith, the blocks shall then be thoroughly rammed to a firm unyielding bed 
with a uniform surface to conform to the grade and crown of the avenue, as shall be directed. 
No ramming shall be done within 25 feet of the face of the work that is being laid ; and the ram- 
ming is to be done at such times and in such manner with reference to the rolling as shall be 
directed. "When the paving from the centre of an intersecting street to the centre of the next 
intersecting street is constructed, it shall be covered with a good, sufficient second coat of clean 
sand, and shall immediately thereafter be thoroughly rammed until the work is made soUd and 
secure, and so on, until the whole of the work embraced in this contract shall have been well and 
faithfully completed in accordance therewith. 

This portion of the work, laid with trap blocks for the gutters, will be measured and in- 
cluded in the returns for Macadam pavement. 

No stone or other material, except sand or granite, is to be placed on the blocks that are 
paved, until these are rammed. When necessary, in order to make good joints, the blocks are to 
be trimmed down on the sides by and at the expense of the contractor. 



CONSTRUCTION AND MAINTENANCE OF ROADS, 103 



APPENDIX NO. 3. 

KOAD EOLLERS. 

As far as known to the writer, the 4 rollers here described are the only ones in the market ; 
they all run with equal facility with either end forward. 

THE GELLEKAT ROLLEK. 

These machines consist espentially of a locomotive boiler, supported on a frame which is car- 
ried on two cast-iron rollers, each 3 feet 11 inches in diameter, and 4 feet T inches long for the 15- 
ton rollers, and 4 feet 9 inches in diameter and 6 feet long for the 30-ton rollers. Their peculiarity 




I I 1 r I I 



THE GELLERAT ROLLER. 



I04 CONSTRUCTION AND MAINTENANCE OF ROADS. 

is that each roller is a driving wheel, and bears half the weight of the machine, -which is guided by 
a hand wheel working from the foot-board into a bevel gear >S', Fig. 2, which works the right and 
left hand screws, jK R, throwing the axes of the rollers into radial positions; the other, or driving 
end of each axle, is stationary, with a spherical bearing — Figs. 1 and 2. 

THE LINDELOF ROLLER. 

This roller has an upright boiler, and two vertical cylinders that actuate a beveled gear which 
works into a gear bolted on to the driving wheel, the tread of which is a 1-inch plate of wrought 
iron ; the driving roller bears two-thiids of the weight of the machine. Both 10 and 15-ton roller* 




THE LINDELOF STEAM ROAD ROLLER. 



are built ; for the 10 ton, of 2,000 pounds each, the driving roller is 6 feet and the steering roller 5- 
feet long, giving a weight on the driving roller per inch run of 185 pounds. 



THE ATELING AND PORTER ROLLER. 

This roller, which is extensively used in this country, has been improved in several par- 
ticulars, and is believed to be the only roller now in the market that is run and fired by one man. 

As now manufactured the outside wheels are the driving wheels, the steering wheels covei-ing 
the space between them. The boiler is horizontal and multitubular ; the single steam jacketed 
cylinder is on top of the boiler, and runs a fly-wheel which by the aid of gearing drives the roller 
at a speed of about 2 miles per hour. The driving wheels have holes in their treads in which 
spikes may be placed for tearing up the road bed before remetalling, and the fly-wheel makes the 
roller available as a stationary engine to run a stone breaker. 

Four sizes are manufactured, viz., 8, 10, 15 and 20 tons in weight. Two-thirds of the weight 
is carried on the driving wheels, which have a width of 2 feet 2 inches for the 20-ton roller, giving 



CONSTRUCTION AND MAINTENANCE OF ROADS, 105 




io6 CONSTRUCTION AND MAINTENANCE OF ROADS, 

a weight per inch run of 574 pounds ; the width of driving wheels on the 15-ton roller, is 1 foot 10 
inches, giving a weight per inch of 509 pounds. The roller is fitted with a friction brake. 

THE BOSS KOLLEK. 

This machine is a combined road roller and rammer. Only one size is built, weighing 44,000 
pounds. The boiler is vertical and the rams, any or all of which can be used or not, are actuated 




by cams. The length of the driving roller is 6 feet in all, vdth a space in the middle of 8 inches 
for the driying chain. The steering roller is 30 inches long. Four-fifths of the entire weight is 
carried by the driving wheel, giving a compressive force per inch run of 550 pounds. It is claimed 
that the traction is sufficient to allow it to mount grades of 20 feet per 100. Maximum speed, 5 
miles per hour. 

The rams, five in number, are said to give an effective blow of 7,000 pounds each ; they are of 
.no use in compressing and puddling trap, but are efficient with limestone, and must be efficacious 



CONSTRUCTION AND MAINTENANCE OF ROADS. 107 

for rubble foundations. The frame is utilized as a water tank, and the driving roller can be 
heated by steam for rolling mastics, &c. 

APPENDIX No. 4. 

A part of the Contract for the, Construction and Maintenance of the Streets and 
Sidewalks of the City of Jassy. 

Between M. Nicholas Gane, Mayor of Jassy, and Mr. W. O. Callender, of London. 

Article 1. The contract has for its objects : 

(a.) The construction of a system of streets with gutters and a system of side n^alks with curbs. 

(6.) The maintenance of the streets and sidewalks constructed under this contract. 

Art. 2. The construction consists of the following items of work : 

(a.) The construction of 47,853.8 square yards of streets, covered with compressed asphalte. 

(&.) The construction of 179,384.3 square yards of sidewalks, covered with asphaltic mastic. 

(g.) The construction of 17,038.4 square yards of roadway, paved with Macadam made from 
stone taken from streets now paved. 

(h.) The construction of 49,210 lin, feet of granite curbing for bordering the asphaltic mastic 
sidewalks on streets covered with compressed asphalte. 

Art. 3. The time fixed for the completion of this contract is five years, to begin with July 
1st, 1873, and to end on March 31st. 1878. 

Art. 5. The labor of maintenance will consist in maintaining the streets in a constant good 
■condition. On all the streets and sidewalks constructed by him, the contractor will repair, with 
his own laborers and his owu material, all degradations as soon as they appear, and will replace, 
the material lost. 

Art. C\ The length of the contract for maintenance is fixed at 15 years, to begin on May 1st, 
18S0, and to end on April SOth, 1895. 

Art. 10. The transverse inclination of the asphalte sidewalks will be 2 per cent. 

Art. 11. The curbs of sidewalks of asphalte, on asphalted streets, will be of granite; those of 
sidewalks c-f asphalte, on streets paved with blocks or cobble stones, will be of sandstone, and 
the curbs of Macadam steeets, when they protect sidewalks of the same material, will be of stone 
cut from the old flagstones of the present sidewalks. 

The curbstones will be of the following dimensions: The faces parallel to the surface of the 
sidewalks will be 5.5 inches in width, of which 0.9 inch of the upper face will be eventually 
covered with asphalte. They will have a height of 11.9 inches, of which 6 inches will be under 
ground and the remainder above the gutter ; their length will not be less than 15| inches. The 
form of the curb will be that of a parallelopipedon, having next the sidewalk a rebate of 0.9 inch 
in width and a height equal to the thickness of the bed of asphalte. 

Art. 14. The gutters of asphalted streets shall have, according to the locality, a maximum 
■width of 3.3 feet ; they shall be constructed of new cobble stones, well culled, or of new sand- 
stone blocks. At the edge of the asphalte there will always be laid a range of granite blocks 10,6 
inches in length, 5.3 inches in width and 9 inches in depth. 

Art. 15. The sandstone blocks for the gutters will be dressed to regular cubes in form, of 9 
inches on each side. 

Art. 16. The asphaltic rock, which must be natural and not artificial, must be from the best 
asphaltic quarries known: Limmer, in Hanover, Seyssel, io France, and Val-de-Travers, in SwJtzer' 
lard. The asphaltic mastic to be used must satisfy the following conditions : 

(a.) It must contain 12 parts of bitumen to 88 parts of asphaltic rock. 

(6.) The asphaltic rock itself must contain at least 7^ per cent, of bitumen, and at the most 93 
per cent, of pure carbonate of lime. 

(c.) Kocks which contain, even in small proportions, quartz, sulphates, iron pyrites or alumi- 
num must be rejected for the composition of mastic. 

Art. 17. The bitumen used for mastic must be natural, not artificial, from the bitumen lakes 
of the Island of Trinidad, or fiom the asi)haltic rocks of Seyssel, if it is proved to be equal in 
quality to the Trinidad bitumen : it must be free from water ; its specific gravity must be from 
1.1 to 1.5. Dipped in water at the freezing point, it must not lose its ductility ; its surface must 



io8 CONSTRUCTION AND MAINTENANCE OF ROADS. 

present no cracks or streaks. The surface of a fracture must be black and brilliant. It must be 
perfectly soluble in petroleum oil or the spirits of turpentine, and the solution when passed 
through a filter must leave no residue. (?) 

Art. 18. The quarry whence comes the bituminous rock, the mastic and the bitumen, must 
be certified by authentic certificates to be of even fabric and its products of the first quality. 
Each block of mastic must bear the trade mark of the quarry. 

Art. 19. The contractor is forbidden to have in his storehouses any asphaltic rock or mastic 
which do not comply with the conditions above stated and not In conformity with the samples 
deposited with the Mayor on the day of the signing of this contract ; he must neither use nor 
have in his storehouses any bituminous or resinous oils other than those specified in Article 17. 

All other material, resinous, bituminous or oleaginous and all other mastic than that like the 
samples deposited with the Mayor that may be found in the storehouses of the contractor will, on 
the first offense be confiscated, and a fine of 1,000 francs be imposed; in case of a repetition of 
the offense, confiscation and a fine of 5,000 francs; aiid should it occur a third time, beside the 
confiscation, the contract will be relet at the expense of the contractor's surety. 

Art. 20. The gravel employed in mixing the mastic must be taken from the beds of streams ; 
it must be thoroughly cleansed of all foreign matter, well washed, free from argillaceous matter,, 
and must be passed through a screen, the holes of which do not exceed 0.2 inch. 

Art. 21. The sand for making the mortar for beton and for forming the bed for asphalte, even 
that employed for bedding the street pavements, the gutters or curbs, shall be sharp, hard to the 
touch, and will be procured from the best open or working pits, or from the bed of running 
water. 

Art. 22, The cement will be the best from the best known quarries, such as Stefanesti or 
Eodeni. 

Art. 23. The stone used in mixing the beton will be broken stone from the quarries of Paun 
or Barnova. Each piece must pass through a ring of 2.4 inches diameter ; it shall be free from 
all foreign matter and well washed. 

Art. 24. The granite shall have the following qualities : 

(a.) It will be obtained from the hardest seams of the quarries ; it shall be homogeneous 
sonorous to the blow of a hammer, without flaws or fractures and free from foreign matter, 

(&.) It shall have a specific gravity of 2.65. 

(c.) After an immersion of 24 hours in water, it must not absorb more than ^Jjj of its volume.. 

(d.) When struck a hard blow, it must break in large fragments without leaving any detritus.. 

Art. 25. The sandstone shall be provided from the hardest beds of the quarries in Eoumania. 
The qualities of the sandstone shall be as follows: 

(a.) Under the blow of a hammer the sound of the stone must be limpid and pure ; a dull 
sound would indicate interior fissures, and would be sufficient to reject it, 

(&.) The specific gravity shall be 2.5. 

(c.) After an immersion of 24 hours in water, it should not absorb more than ^^^ ot its volume. 

Art. 26. The limestone for the beton shall be of the hardest quality, chosen from the hardest 
beds. 

Art. 27. The mortar for the beton of the sidewalks shall be composed of two parts of sand 
to one part of cement in volume. It shall all be mixed and wet with only as much water as may 
be absolutely necessary. Mortar which may set before being put in place will be rejected. 
The composition of the mortar for the beton which is to be used on the streets remains to be 
described hereafter, as also the compressed asphalte. 

Art, 28. The beton will be composed of three parts of broken stone to two parts of mortar. 

The beton which is not used after it is prepared will not be accepted. 

The streets which are to be covered with compressed asphalte shall be constructed in the 
following manner : 

(a.) The levels will be corrected, the ground shall be shaped to the form of the transverse pro- 
file fixed by the city, and will be sprinkled and rolled until it pres«»nts a smooth, hard surface, 

(&,) The curbstones shall then be set, care being taken to cut the joints on the ends as well 
as on the front edge, 

(c.) The part corresponding to the gutters will then be made of a bed of sand 2.4 inches in 
depth, in which will be laid the stones which form the gutters ; the sides of the gutters next to the 



CONSTRUCTION AND MAINTENANCE OF ROADS. 109 

"bed of asphalte will in every case have a range of granite blocks. The remainder of the width of the 
gutters shall be paved ^^^th cobble stones, well assorted, in such a manner that the stones will all 
be of the same size, or with new sandstone blocks, agreeably to the city authorities. The gutters 
thus laid shall be well rammed wth a rammer, and over all shall be spread a layer of sand 0.4 
inch deep. 

(c? .) That portion of the street which is to be covered with asphalte, will receive a bed of 
heton, the depth of which, after pilonnage, shall not be less than 6 inches. Upon the beton shall 
be spread a layer of brick broken to 0.4 inch in size. 

(e.) On this shall be laid the compressed asphalte, when the foundation shall have reached the 
desired consistency and become well dried. 

(/.) The asphalte will be laid according to the methods usually adopted on works of a similar 
nature ; the method of doing this remains to be discussed at a future day by the city and the con- 
tractor. 

Art. 33. The surface of the sidewalks shall be done over when needed, sprinkled and rolled ; 
over this shall be laid a bed of beton which after compression shall not have a less thickness than 
3 inches. On this shall be spread the mastic to a depth of 0.8 inch. This mastic shall be com- 
posed of asphaltic mastic, gravel and bitumen in the following proportions : Asphaltic mastic 100 
parts, gravel 60 to 72 parts, and bitumen 6 to 10 parts. The mastic and bitumen shall be melted 
in a portable kettle, so that they may be carried to the spot where they are to be used. The mas- 
tic shall be broken into small pieces, and shall not be poured until it is entirely melted. Durmg 
the melting the mastic shall be kept stirred, so that a thorough mixture may be insured and the 
mastic not allowed to burn. The mastic thus prepared shall be run over the beton in such a man- 
ner as to spread evenly over it. Before the complete solidification of the mastic which foi-ms the 
surface, sand will be spread over it and fixed by light ramming. At the junction between a cold 
and a hot bed, the edge of the cold one shall be reheated by spreading over it a coating of melted 
bitumen that wll then be removed and the final bed laid. 

Akt. &4. The tempering of the mastic should be such that it will support, at a temperature 
of 77 Far., the point of a rectangular pyramid of a height equal to one side of the base, without 
a depression occurring greater than 0.2 inch under a pressure of 154 pounds continued for five 
minutes. 

Art. 35. The sidewalks at carriage doorways shall have a foundation of beton 4 inches in 
depth after ramming, and the bed of mastic will be 1.2 inches. 

Art. 37. The junction of the mastic with the walls of the buildings bordering the streets will 
be made by means of a skirting, that is to say, the plaster will be scraped from the walls of these 
houses to a height of 2 inches above the level of the sidewalks, and the asphalte will be plastered 
on the bricks to the thickness of the mortar. 

The junction of the stratum of mastic with the posts, curbs, hydrants, and other objects of 
various natures will be made by heating these objects by a coating of melted asphalte that will be 
then removed and the final bed laid. 

Art. 42. The blocks and the cobble stones that the city authorities may declare unfit for using 
-again \s\\\ be broken and used as Macadam on streets designated by the city ; they shall be con- 
structed as follows : 

(a.) The ground shall be well graded, giving it the form and inclination of similar 
streets. 

(6.) On the surface thus prepared there shall be laid first, gutters of cobble stones to a width 
of from 2.5 to 3,3 feet. These shall be laid as specified for streets paved with cobble stones. 

(c.) On that portion of the ground designed for the roadway there shall be spread a bed 
of broken stone of 6 to 8 inches, reducing, after wetting and ramming, to 4 to 6 inches in 
depth. 

id.) On this strata of stone there shall be spread a bed of sand, which shall be well wet and 
rolled, so as to obtain a smooth and uniform surface. 

Art. 49. * * * * From the provisional recepfion, the maintenance of the 
work completed wll be performed by the contractor till April 30th, 1880. 

Art. 50. All unexpected degradations, all badly executed work, not only during the progress 
of construction, but also during the years of maintenance, will be repaired by the contractor, what- 
ever may be the cause of the degradation, and with the least delay, without waiting to be notified 



no CONSTRUCTION AND MAINTENANCE OF ROADS. 

by the city, under penalty of a fine ot 50 francs for each diiy of delay after the three first days 
Avhlch follow that of the discovery of the degradation. 

Besides that penalty, if the contractor does not proceed immediately to the reparation of these 
unforeseen accidents, the city shall have the authority to put them in good repair in his place 
and at his expense, by deducting the cost from the estimate. 

Akt. 51. On April 1st, 1878, the city will make a new and minate inspection of all the work 
done during the five seasons. They will compare the state of the work done with that of each of 
the estimates made at the end of each season, and if it be found that the works are in compliance 
with this contract, and in good condition, they will finally accept them and make out a new esti- 
mate, of which a duly certified copy will be furnished the contractor. 

Art. 52. On May 1st, 1880, the contractor having satisfied the first part of the obligations de- 
volving upon him under this contract, binds himself under a new obligation to the city, that of 
maintaining for a period of fifteen years, from May 1st, 1880, to April 30th, 1895, the works exe- 
cuted, in consideration of a price agreed upon in advance. 

Art. 53. The maintenance consists in repairs, renewals and furnishing materials necessary to 
the sidewalks, curbs, gutters, etc. ; in doing all kinds of work and furnishing materials necessary 
to at all times maintain the surface of the streets and sidewalks paved by the contractor, in a per- 
fect state of uniformity. 

The uniformity of the surface of the streets and sidewalks shall be determined by the use of 
a templet of iron formed to the normal curve adopted for the surface of the streets and sidewalks. 
This templet, applied to a street or sidewalk, must not present at any point a swell or depression 
greater than 0.4 inch. 

The surface of the streets and sidewalks shall not show any cracks. The connections witk 
the curbs must be perfect. 

Art. 54. "Whenever the curbs, the sidewalks, the roadways, the water ways — in a word. 
everything that goes to make a part of the street, becomes subject to a displacement or derange- 
ment from any cause whatever, the contractor will be obliged to repair them immediately, in con- 
formity to the preceding article. Exception is made, however, to all that applies to the construc- 
tion or repairs of water or gas mains, which will always be at the expense of the respective 
grantees. 

Art. 55. The contractor shall proceed at once, at his own cost, to repair any degradation 
whatever, without notification from the city. 

Whenever a notification from the city becomes necessary to warn him to proceed with the re_ 
paration, the contractor will be liable to a fine of ten francs, and he will be obliged to proceed 
with the reparation within 24 hours after the receipt of such notification. 

If, after that notice, the contractor fails to proceed with the repairs of the degradation indi- 
cated by the citj^, the latter shall proceed with the work ; it shall make the reparation, submit the 
contractor to a fine of fifty francs, and retain the cost of the reparation and fine from any sums 
that may accrue for the maintenance of the streets, and in case that should not be sufficient, from 
the sureties. 

In case of a repetition of this offense occurring during the cours% of a single year, the city, be- 
sides the right which it always reserves to make the reparation on the account of the contractor, 
in conformity with the preceding paragraph, will impose ou the contractor a fine of 1,000^ 
francs. 

Finally, on a third infraction in the course of the same year, the city has the right to make 
besides the reparations after the rules estabfished above, and of re-letting the work of maintenance 
to another at the cost of the contractor ; if this sale results in a loss to the city, it shall have the 
right to reimburse itself from the sureties. In case, on the contrary, it results In a profit, th& 
contractor shall have no right to demand it. 

Art. 59. The prices for the works executed in conformity to the requirements of this contract 
shall be : 

(a.) For compressed asphalte, $5.38 per square yard. 

(6.) For sidewalk asphalted, $2.81 per square yard. 

(c.) For roadway, with gutters, paved with sandstone blocks taken from streets now paved,. 
$1.94 per square yard, 

(d.) For roadway or gutters paved with new sandstone blocks furnished by the contractor^ 
$8.41 per square yard. 



CONSTRUCTION AND MAINTENANCE OF ROADS, iir 

(e.) Forroadwaj-, the gutters included, paved with cobble stones taken from streets now 
paved in that manner, also for gutters constructed with cobble stones on Macadamized streets, 
$1.02 per square yard, 

(f.) For roadway paved with cobble stones furnished by the contract ir, also for gutters paved 
in this manner on streets covered with compressed asphalte, $1.91 per square yard. 

(g.) For Macadam roadway, $1.45 per square yard. 

(h.) For granite curb to asphalted sidewalks, $0.95 per lineal foot. 

(i.) For sandstone curb to asphalted sidewalks, $0.67 per lineal foot. 

(fc.) For curb cut from the old sandstone s;abs or flags. $0.39 per lineal foot. 

(l,) For granite curb used in the edging for asphalte of streets, $0.81 per lineal foot. 

Art 57. The price for maintaining the roadway and sidewalks during 15 years from May 1st, 
ISSO, to April 80th, 1S95, shall be calculated from the total area constructed by the contractor, and 
shall be as follows : 

(a,) For maintaining compressed asphalte streets with granite curb, $0.09 per square yard 
per annum. 

(&.) For maintaining asphalte sidewalk, whatever the kind of curb, $0.04^ per square yard per 
annum. 

ic.) For maintaining roadwaj^ or gutter paved with old or new stone blocks, $0.29 per square 
yard per annum. 

{d.) For maintaining roadway or gutters paved with cobble stones, $0.09 per square yard per 
annum. 

(e.) For maintaining Macadam, including the sidewalks and curbs, $0,15 per square yard per 
annum. 

Art. 5S. Payment for work done will be made to the contractor in the following manner: 

One-quarter of the work done will be paid for in cash, the remainder in City bonds. 

The bonds will have 15 years to run ; they will bear interest at 6 per cent, per annum, pay- 
able semi-annually ; they will be deUvered to the contractor at par. 

Art. 67. The sums due for the maintenance of streets and sidewalks during the 15 years 
which follow the construction— from May 1st, 1880, to April 30th, 1S95 — will be paid by the 
City of Jassy, at the end of each month, after deducting all that the contractor owes to the City 
for repairs made in his name and at his expense, and fines. These payments will be made in gsA. 

arts. 69 to 71, inclusive, provide that the contractor shall place a guaranty of 100,000 fvimf?, 
in bonds of Eoumania, which may be replaced by bonds of the City. In addition 10 i)er cent, of 
contract price shall be retained, until the sum of 400,000 francs is reached, making a total guaranty 
of 500,000 francs. This guaranty shall be returned to him as follows: May 1st, 1878, 250,000 
francs ; and at the end of the years ot maintenance. May 1st, 1895, 250,000 francs. 

Art. 72. Six months before the expiration of the fifteen years of maintenance, the City 
authorities will make a general .inspection of all the work done and maintained and make an 
estimate of it. 

Art. 73. If during this inspection the City discovers the necessity of any repairs, the con- 
tractor shall do the same at his own expense during the following six months, in such a manner 
that the streets maintained by him shall be turned over to the City in a good condition on the 
day the contractor completes his contract. 

Should the contractor refuse to make these repairs, the city shall proceed to do it at the ex- 
pense of his warranty. 

Art. 74. At the end of the 15 years of maintenance, if the streets are in a good condition, 
considering only the effects of the weather, but presenting no degradations, the final acceptance 
of the works will be made and the guaranty deposited by the contractor returned to him. 

The coupons of bonds deposited as guaranties are the property of the contractor, who will 
have the right to collect the sums corresponding to each. The contractor shall also have the 
right to replace the bonds deposited by him as guaranty whenever they may become extinguished 
through the process of drawing lots. 

Art. 89. The system allowed for the pavement of the carriage wi:ys is that of compressed 
asphalte. The manufacture of this compressed asphalte will not depart from the rules actually 
adopted by science and experience, the mode of execution of the compressed asphalte remains to 
be agreed upon hereafter between the City and the contractor. 



112 CONSTRUCTION AND MAINTENANCE OF ROADS. 

APPENDIX No. 5. 

Abstract of Specifications and Schedule of prices for the construction and main- 
tenance of foot-paths and sidewalks, in asphaltic mastic, and the Places and 
roadways in compressed asphalte belonging to Municipal service of Paris, 
from January 1st, 1878, to December 3lst. 1882. Paul Crochet, Contractor. 

Article 1. The work has for its object— 1st. The maintenance and construction of foot 
paths and sidewalks in asphaltic mastic, situated in the pubhc ways. 2d. The maintenance and 
construction of compressed asphalte pavements. 3d. The new works ; these works will com- 
prise all the pavements in bitumen and asphalte. 

Art. 4.— The present letting is made on a scale of prices, and the amount of the work is 
completely undefined, so that the contractor cannot make any demand on account of any changes 
that the expenditure may be subject to. 

Art. 6. When the adjoining proprietors or other parties in interest have to bear the cost of the 
works detailed above, or to contribute in any proportion, the contractor will be held to execute 
the work at the same price as that done at the cost of the City of Paris, and conformably to the 
■orders of the Engineers. 

Art. 7. Foot pavements shall have the widths determined by the administration, they shall be 
composed of pavement in mastic supported on the side of a public road by a curb the height of 
which shall commonly be of 6^ to 4 inches. 

Art. 9. The ordinary curbs in gi-anite shall be llf inches wide on top with a total fall across 
off inch ; 13 inches wide at the base, which shall be horizontal ; llf inches high on the front face, 
which shall have a batter of 1^ inches. 

Art. 16. The mastic pavements will be formed of a layer of pure asphaltic mastic at least x% 
inch thick, resting on a bed of hydraulic concrete 4 inches thick which comprises a covering of 
hydraulic mortar at least f inch thick. 

Art. 17. The compressed asphalte pavements will consist of an upper layer of compressed 
asphalte 1^ to 2i inches thick, resting on a foundation of hydraulic lime or cement, concrete 4 to 
6 inches thick covered as above with mortar or upon an old Macadam roadway picked over and 
covered with a thin coat of hydraulic mortar. 

Art. 21. The asphaltic mastic employed either for new or repairing old paving shall be com- 
posed of naturally impregnated rock with natural bitumen of good quality, coming exclusively 
-from mineral rocks. 

The fictitious bitumens extracted by the purification of the heavy oils of schists, the distilla- 
tion of coal, those so-called fatty bitumens and all other analogous products shall be rigorously 
proscribed. 

The rock employed after being reduced to powder will be melted with a sufficient quantity of 
purified natural bitumen to form a mastic which, when cold, presents a homologous mass slightly 
elastic, and which does not soften under a hot sun. This mastic shall be moulded into blocks. 
There may also be used blocks of bituminous mastic with a base of slates manufactured by the 
process of M. Sebille. 

Art. 22. The contractor shall be bound to employ under the orders of the Engineer upon 
each public way the bituminous mastic above described. 

The mastic shall be formed of a mixture of natural bitumen, in the proportion of one-twelfth 
of its weight at most, and the calcareous asphalte rocks of Seyssel, Seyssel-Forens, Pyrimont or 
Volants, of Val de Travers or Lobsan, or others deemed equivalents by the Engineers. 

The mastic, having a bas« of slate of M. Sebille, will be formed of a mixture of bitumen 
described in Art. 23, following, and of powdered red or blue slate of Ardennes, powdered chalk of 
Mendon or of Nanterre and of silica from the basin of Paris, in the following proportions, by 
weight : 

Eefined mineral bitumen 30 

Ground slate 35 

Powdered chalk 10 

Silica, ground and sifted -, 25 

100 



CONSTRUCTION AND MAINTENANCE OF ROADS. 113 

Art. 23. Ihe bitumen shall come as much as possible from the washings of bituminous 
sandstone or the asphaltic rock of Maestu, and in their default, from the dry pitch of Trinidad, 
perfectly pu'ified. It ought to be viscid at the ordinary temperature ; never brittle or liquid ; 
drawn into threads it should lengthen and only break in very fine points. 

Art. 24. The rock employed should be calcareou!», soft, with fine grain, texture fairly com- 
pact, regularly impregnated with bitumen so as not to show black and white spots ; it should be 
of a brown color ; heated to 122 to 140° F. it should soften and break on being torn. Care must 
be aken for the areas in asphalte to choose only such pieces as are of the most even grain and 
richest impregnation. The rock of Lobsan, however, should not be employed alone in the 
asphalte roadways, it ought to be mixed with other rocks less fat in proportions, which will be de- 
termined by the Engineers according to the composition of the other rocks. It should contain 
at least 7 per cent, of bitumen, and at the most 93 per cent, of lime; its change into mastic 
must not require more than 9 per cent, of bitumen. 

Art. 25. The materials entering into the composition of the pavements are the mastics 
described in Art. 22, pure gravel grit and natural bitumen to assist the melting. These materials 
ought to be generally employed in the following proportions, by weight: 

( Asphaltic mastic 100 

Foot pavements with a base of asphalte. .K Bitumen 6 

( Grit 60 

( Asphaltic mastic 100 

Foot pavements with a base of slate •< Bitumen T 

/ Gravel 50 



Art. 26. One month before the award of this contract the competitors must deposit at the 
office of the works in Paris, samples of— 1st, A block of the mastic described above; 2d, Speci- 
mens of the asphaltic rocks and the natural bitumens they intend to use; 3d, A note indicating 
the elements of the composition of the mastics and proportions of the various rocks that they 
intend to employ in the composition of the asphaltic areas. 

The blocks and specimens of rocks and bitumen to have the trade-marks of the works from 
whence they came and the signatures of the competitors. 

The necessary certificates to compete for the contract will not be delivered till after the 
examination and acceptance by the Engineers of the specimens deposited. During all the 
term of this contract the contractor can only use materials exactly similar to the sjjecimens de- 
posited. 

Art. 27. Provides for continuous inspection of the contractor's works or the right to compel 
the contractor to manufacture the mastic in the depots belonging to the city. 

Art. 31. The lime employed is to be hydraulic lime in powder. It must be brought onto the 
works in sealed bags, marked wiih the name of the maker. Only the lime and cement designated 
in the specifications for the construction and repair of sewers will be allowed. 

A3T. 32. The broken flint must pass through a ring of 2^ inches and be at least |-inch thick. 
It must be free from earthy matters and washed clean. 

Art. 33. The sand shall be dredged from the Seine and well cleansed from all foreign matter; 
it shall be screened from all grains larger than | inch for the mortars, or ^% inch for grit 
for the mastic pavements; the grit for this last purpose shall be perfectly washed and dried before 
use. 

Art. 34. The mortar of hydraulic lime shall be composed of 5 parts of sand and 2 parts of 
lime, by volume, furnished in powdeu; the mixture shall be directly reduced to a paste by adding 
the quantity of water exacth' required to reduce it to the consistency of plastic clay. 

The cement mortar shall be composed of one part of hydraulic cement of Bourgogne or Port- 
land cement of Boulogne and 3 parts of sand; the sand and cement shall be thoroughly mixed 
before the addition of any water. All mortar which shall have set shall be rejected. 

Art. 35. The beton shall be composed, ordinarily, of two parts in volume of mortar and three 
of stone. The mixture, made either by the rake or cylinder, must be perfectly uniform. 

All beton not used at the time of making shall be rejected. 

Art, 86. The bed of beton for the foundation of the sidewalks shall be well rammed and com- 
pressed, and must at least commence to set and dry before receiving mastic or asphalte. The 
beton shall, In addition, be covered with a layer of mortar f inch thick. 



114 CONSTRUCTION AND MAINTENANCE OF ROADS. 

The gravel for foundation shall pass in every direction through £ ring 2 inches in diameter. 
It must be perfectly compressed and sprinkled wlthlime grout. This foundation shall have com- 
menced to set before the application of the mastic, and shall be covered with a layer of mortar 
like the beton. 

Art. 39. The ground upon which the mastic pavement is to b-^ placed shall always be pre- 
viously rammed, watered, and crowned with care. When it is thus made solid the contractor 
shall spread over it the foundation layer, formed according to the orders of the Engineer, either a 
bed of beton or of sand covered by a Lyer of mortar, or a bed of sand impregnated with goudron 
2f inches thick, or any other foundation prescribed by the Engineer. 

In all cases the pavement shall not be laid till the foundation has attained the firmness 
desired, and become quite dry. 

The contractor must conform to the following orders for the manufacture of the mastic to be 
used for pavements. 

The mastic shall be prepared and cast in one or more manufactories belonging to the con- 
tractor, and which shall always remain open to the inspection of the engineers and their agents. 

The contractor sha'.l, besides, establish in the manufacturing depots, both of asphalte and 
mastic, oflSces exclusively for the agents of the administration set apart for the inspection of the 
composition of these materials. These materials shall not be admitted into the works without a 
cai-ter's delivery note given by the inspector, setting forth that they have been manufactured in 
accordance with the specifications. 

There shall only be allowed in the works blocks of mastic conforming to the samples de- 
posited and accepted before the award, and bearing their trade-mark, or the old mastics from the 
walks and streets of Paris. All other bituminous matters, resinous or fatty, found in the works 
by the agents of the administiation will subject the contractor to a deduction of $100 for each 
time. 

To assure the execution of these conditions the contractor must not have in any manufactory, 
under the same penalty, any other blocks than those which should be prepared in his works, and 
the old mastics taken up. 

The use of the old mastic is authorized in the works of the city in the proportion of one-half 
with the new. The pieces of the old sidewalks having been perfectly cleaned with great care, 
and regenerated by the addition of new purified bitumen and a suflacient quantity of powdered 
asphalte to render the old mastic, when melted, of the aspect and consistence of the blocks in 
fusion. 

This mastic shall be melted in hermetically closed boilers, on wheels of a model approved by 
the administration, and arranged so that the material can be conveyed from the factory to the 
place to be used, ready to be employed. 

For melting, the mastic is broken into pieces 4 inches cube, then the bitumen is melted and 
the mastic added little by little. 

The grit must not be thrown into the boiler till the mastic is completely dissolved. 

During the whole time of the operation the matter must be stirred up almost constantly, so 
that the combination shall be well made and the mastic not burned. 

The mastic being well melted and perfectly homogeneous, it shall be run out in bands of 
about 5 feet wide, spread with a wooden float, and leveled with a strike, so as to present neither 
fissure nor joint. The mastic must be perfectly level, and match exactly with the curbs, &c., 
against which it is laid. For this purpose {he parts of the curbs, flags, Ac, which will be in con- 
tact with the bitumen shall be previously warmed and goudroned. 

Art. 40. Upon the soil, well shaped and rammed, shall be placed a bed of concrete, covered 
with a layer of mortar. 

The asphaltic rock, conforming to Article 24, broken down or decrepitated by heat, shall be 
raised to a uniform temperature of Irom 248° to 266° F., and carried to the place of employment 
in vehicles that will prevent as much as possible the loss of heat. It must be completely freed 
from the water it contains. The use of old compressed, taken from old roads, is authorized for 
mixture with new asphalte, in the proportion of one quarter of old compressed to three-quarters 
of new rock, provided that the old shall be cleansed with great care before grinding and mixing 
with the' new. 

Asphalte shall not be put on the concrete foundation until it is peerfectly set and dry. 



CONSTRUCTION AND MAINTENANCE OF ROADS. ii$ 

The powder shall be spread with a thickness about two-fifths inore than the finished thick- 
ness, leveled with great care, shall be rammed at first carefullj^ then gradually augmenting the 
force by means of cast-iron pilons, heated to the proper temperature in portable furnaces. In 
specially exceptional cases, the compression may also, wth the written permission of the Engineer 
be accompHshed by means of rollers. 

In every case, after the pilonnage is finished, the surface shall be smoothed by means of % 
heat-'d iron Uissoir). 

The road shall not be open to traflic until it is quite cool. 

Art. 41. The specifications referring to the construction of roads and footpaths are applicable 
to the maintenance of the same. The contractor will be entitled to the old material, and will 
make the repairs in new material or in the mixture specified in Articles 39 and 40. 

Art. 43. In conformity Avlth the contract price, stipulated hereafter, diminished by the 
rebate of the awarded contract, the contractor must make the necessary repairs to all asphaltic 
mastic footpaths and areas, furnishing the necessary labor and materials, so that they shall be 
kept in a proper state. He must each 3'ear of the duration of the contract completely relay, in 
new material, at least the fifteenth part of the surfaces of masr tic and compressed asphalte. The 
surlaces in mastic must be properly plane and regular, presenting neither hollows nor projections' 
of more than three-eighths of an inch in a circle whose radius is Z\ feet. These surfaces must be 
free from fissures. 

Art. 45. As the works in asphalte or mastic are received by the engineers thej' will pass into 
the charge of the contractor who will receive for the maintenance the price stipulated, commenc- 
ing from the 1st of January next following their acceptance, whatever may be the date of said 
acceptance. 

Art. 46., The contract prices diminished by the rebate of the award are applicable to the entire 
surface occupied by footpaths or compressed asphalte, whatever may be their condition. 

In the nine last months of thq year installments may be paid on the contract when the engi- 
neers recognize that the conditions have been loyally carried out. The accumulated sums of these 
installments must not exceed four-fifths of the amount of the sums which shall be due after the 
time has expired. The balance of the contract price of the year will be paid in the course of the 
first quarter of the following year. 

Art. 47. The repairs over trenches for sewers, water and gas-pipes, or other works, will be 
paid for once at the schedule price, but no demand for further payments on account of sinkings 
or other dilapidations will be entertained, and the surfaces on these trenches must be kept in the 
same good condition as the others. For the purpose of securing settlement, the contractor may- 
keep the trenches repaired with flint (Macadam) not longer than 15 diys. 

Art. 49. All damages in the bituminous surface, such as fissures or cracks of at least ^'g inch 
in width, or parting from the curbs y'g inch in width, any lifting up or breaking away of the 
mastic for at least j^'g in depth, depression in consequence of settlement of f inch at least in depth 
under the straight edge, 3J feet long, will subject the contractor to a deduction of 3 francs (58 
cents) per day, when the repairs shall not have been done within 48 hours after notice given by 
the Engineer. 

Art. 51. During the continuance of frost, and during the first month after the commence- 
ment of the thaw, there shall be no repairs to the pavements maintained by the contractor, and 
the inspection for defects shall be suspended, but the contractor shall fill with sand and gravel any 
holes in these pavements within 24 hours after notification by the Engineer, under a penalty of 10 
francs ($1.9;3) for each day they remain unfilled. He may be authorized, in exceptional cases, to 
fill the holes with broken flint or melted bitumen, but must replace the flint or bitumen with 
as-^halte as soon as the weather permits. It must be so arranged that the main repairs, intended; 
to re-establish the normal outline of the roadways, are effected from May Ist to November 1st. 

Art. 57. The contractor shall execute in private houses the junctions rendered necessary by 
changes in the public way, which will be paid for according to the price of his contract, subject to 
the rebate when the works are executed on account of the city. 

Art. 65. When a workman leaves one of the districts of the works under the Municipal ser- 
vice, he must have a certificate from the contractor showing the cause for which he left. 

This certificate shall be submitted at once to the Engineer, who shall be at liberty to refuse 
the right of employing the said workman, without the contractor deriving therefrom any excuse 



ii6 CONSTRUCTION AND MAINTENANCE OF ROADS. 

for not furnishing, when requisite, the number of -workmen required. In default of a certificate, 
the workman cannot be admitted, except on the written order of the Engineer. 

Note. — There are 75 articles in this contract, those not given referring to the setting of curbs, 
etc., transport of materials, and the relations between the Engineer and contractor. 



SCHEDULE OF THE PRICES FOR THE WORK SPECIFIED 

ABOVE. 



Note. —All the prices below comprise the incidental expenses and the profits of the contractor 
and are subject to the rebate of the award. 

(This contract is let in three lots, the rebates are 7j?, 20.2^, and 14$^, respectively.) 

Day Work.— The day of a workman, cart or machine shall be ten hours of efl'ective work in 
all seasons ; fractions more or less shall be counted by the hour, or ^^j of the day. 

The night hours shall be paid half as much more as those of the day, excepting watchmen. 
Night hours will be counted only from 7 p. m. to 5 a. m. in summer, and from 5 p. m. to 7 A. m, in 
winter. The summer period begins March 1st, and winter November 1st. 

1. A day of a laborer , 9&i 

2. " an ordinary mason 1.06 

8. " an asphalte helper, or of a mason's or paver's helper 87 

4. •' granite cutter 1.35 

5. " sandstone cutters, pavers and asphalte workers 1.26^^ 

6. " watchman ' 53 

7. Night watchman 79 

8. Day of one-horse wagon and driver. ., 2.70 

9. •' two-horse " " 4.05 

21. 1 cubic yard of stone broken for concrete 1.22 

22. " ground hydraulic cement 513 

23. " river sand 1.18 

24. " pit sand 89 

25. " river sand, washed and dried for mastic 1.48 

27. 100 pounds of Roman cement 58 

28. " Portland cement 67 

29. " asphaltic rock 68 

30. " mineral goudron, from Lobsang, Bastennes, or other recognized as 
equivalent to them, and purified Trinidad or Maestu . . 3.24 

49. 1 cubic yard of mortar, composed of two parts of ground hydraulic lime and five 

parts of sand 3.10 

50. 1 cubic yard of mortar, composed of one part of hydraulic cement uf Bourgoyne 

and three parts of .«and 5.02 

51. 1 cubic yard of mortar, composed of one part of Portland cement and three parts of 

sand 6.42 

52. 1 cubic yard of concrete, composed of three parts of broken stone and two parts of 

mortar ( J^To. 49) 8.03 

63. 1 cubic yard of concrete, composed of three parts of stone and two parts of mortar 

(No. "50) 3.99 

64. 1 cubic yard of concrete, with mortar (No . 51 ) • 4.65 

55. 100 pounds of natural bituminous mastic in blocks, made from rock of Seyssel, or 

other equivalent, ready to be employed 1.02 

6[). 100 pounds of compressed asphalte, taken from streets to be repaired, shall be taken 

by the contractor (without rebate) at 35 

61. 1 square yard of old sidewalks in mastic shall be taken by the contractor, without 

retrard to its thickness and without rebate, at , 19 

70. Taking up 1 square yard of compressed asphalte, piling the material included 014 

71. Taking xap 1 square yard of mastic sidewalk, with piling the material 003 

73. Cleaning and leveling an old Macadam road to secure a surface of mortar for com- 
pressed asphalte, per square yard 10 

93. 1 square yard of new natural a«phaltic mastic, 0.6 inch thick 53 

94. Greater or less value of each x^ of an inch in thickness 045 

95. 1 square yard of sidewalk relaid in natural asphaltic mastic, 0.6 inch thick, the old 

material belonging to contractor 40 

96. Greater or less value of each -^%^ inch in thickness 025 

97. 1 square yard of pavement, 0.6 inch thick, composed of one-half new and one-half 

new and one-hnlf old mastic 50 

98. 1 square yard of repairs of pavements composed as above 32 

99. For each j§g in thickness, more or less 02 



CONSTRUCTION AND MAINTENANCE OF ROADS. 117 

102. 1 square yard of compressed asphalte, 1.6 inches thick, comprising regulating the 

surface of the ground, hut neither excavation, embankment nor foundation of con- 
cret-^ 173 

103. For each i Jo in thickness, more or less 17 

105. 1 square yard repairs of road 1.6 inches thick, the contractor retaining the old ma- 

tt-rial 1.04 

106. For each ^%^ in thickness, more or less 17 

lOS. 1 square yard of foundation for pavement in asphalte or mastic, comprising regulat- 

in'g aid ramming the roadbed, but not excavation. 

109. 1 square yard concrete of hydraulic cement rammed to 4 inches] in thickness, com- 

prising a covering of mortar. No. 49, at least j J^ inch thick 34 

110. 1 square yard concrete of cement. No. 53, rammed to 4 inches thick, comprising a 

covering of mortar, No. 50 46 

111. 1 square yard concrete of cement, No. 54, rammed 4 inches thick, covered with 

mortar No. 51 54 

112. 1 square yard on natural soil, with a bed of sand 0.8 inch thick . . 04 

117. Kepairs in which all or a part of the old materials are used, will be paid for at three- 
quarters of the prices above mentioned. 

207. 1 square yard of sidewalk, in natural mastic, half an inch thick, comprising a hydraulic 

hme concrete foundation, 4 inches thick after ramming, with regulating but not ex- 
cavatinar 93 

208. Note. When the foundation is in cement concrete the price above will be increased 

hy the respective dillerences between each of the prices of Nos. 110 and 111, and 
that of 109. 

209. 1 square yard of mastic like 207, on the natural ground, covered with a bed of sand 0.8 

inch thick 63 

210. 1 square yard of mastic Hke 207, on the natural ground, covered with hydraulic mor- 

tar 6a 

211. Note. When the pavement is one-half new mastic with old material, the prices above 

will be dimished by 09 

812. 1 square yard of compressed asphalte 1.6 inches thick, including a foundation of hy- 
draulic lime concrete, rammed 4 inches thick. Including dressing and ramming the 

soil but not excavation 2.07 

213. 1 square yard of compressed, with concrete of cement No. 51 , 2.21 

Additional price for work executed on embankments more than 1 yard high, or on 
trenches, whatever may be the thickness of the pavement or concrete. 

215. 1 square yard of mastic 22 

216. " " compressed 36 

217. Maintenance of 1 square yard of sidewalk in asphaltic mastic, in conformity with these 

specifications, per annum ■ 05 

218. The same for roads in compressed asphalte 19- 

219. Additional price for maintaining cross-walks of compressed asphalte on Macadamized 

roads, and of gutters bordering them 10 

248. For works not mentioned in the present schedule, che prices in the schedules now in 
force for maintenance of public ways or sewers and water service will be paid: 
which prices will be subject to the rebate of the present letting. 



DISCUSSION ON 

THE CONSTRUCTION AND MAINTENANCE OF 

ROADS. 



By Arthur Spielman and Charles B. Brush, George D. Ansley, 
A. B. Hill, Charles Douglas Fox, E. Lavoinne, E. B. Van 
Winkle, B. F. Morse, E. S. Chesbrough, E. R. An- 
drews, C. Shaler Smith, M. Merriwether, 
J.E. Hilgard, D. E. McComb, F. Rinecker, 
J. J. R. Croes, John Bogart, C. C. 
Martin and Edward P. North. 



A. Spielman and Charles B. Brush (Spielman & Brush). — 
Some of the views expressed in Mr. North's paper on "the construction 
and maintenance of roads," being at variance with the results of the ex- 
perience of our firm, in the building of 36,000 square yards of Telford roads 
in 1875 and 1876, and about 25,000 square yards in 1878 and 1879, part of 
this latter am'^unt being now in the course of construction, we herewith 
submit the principal facts in relation to these roads, and our conclusions 
therefrom. 

The roads are 80 feet wide between house lines, and are located in the 
northern part of Hudson County, New Jersey ; they are built exclusively of 
trap rock, obtained from and along the line of the road, the stone for the 
upper courses having been broken by a stone crusher erected on the road 
by the contractor, the average haul from the crusher not exceeding 2,000 
feet. No binding except the screenings and detritus of the stone was al- 
lowed in the work, and in each case the foundation is of rubble, 8 inches 
deep, and the superstructure of broken stone, 4 inches thick, when com- 
pacted. 

The roads built under our direction in 1875-1876 may be divided into 
two classes : 

1. Roads by the side of horse railroad tracks. 

2. Roads free from horse railroad tracks. 



I20 CONSTRUCTION AND MAINTENANCE OF ROADS. 

In the first case the width of the roadway from curb to curb is 55 feet, 
which includes 18 feet of trap block pavehient for the tracks, and 5 feet for 
the gutter. 

In the second case the width between the curbs is 40 feet, including 5 
feet of block pavement for the gutter. 

In both cases the 8-inch foundation was first carefully laid, and great 
care taken to allow for perfect sub-drainage. Cess-pools, filled in with 
broken stone, were built at intervals of about 200 feet on both sides of the 
road, which collect all the water that accumulates in the foundation of the 
pavement, and these cess-pools are drained by 6-inch stoneware pipes into 
adjoining receiving basins. 

A particular illustration of the importance of this sub-drainage came 
under our notice. In December, 1875, just after considerable of the foun- 
dation had been laid, legal difficulties arose, the work was suddenly 
stopped, and remained in this unfinished condition until the spring of i876» 
receiving in the meantime the wash from the adjoining hill-sides. When 
the work was recommenced the interstices between the foundation stones 
of the pavement in many places were filled in with earth. After unsuccess- 
fully attempting to remove this earth, the foundation at these points, as 
far as they could be ascertained, was taken up and relaid : but as soon as 
the superstructure of the road was completed we found that, in certain 
spots, it was always wet, and the surface of the road was continually 
broken. These spots invariably indicated the points where the foundation 
was clogged, and the difficulty was only effectually remedied by relaying 
the foundation, or by building blind drains which carry off the accumulat- 
ing water. 

On the top of the foundation thus prepared, 2-inch stone was then put 
on, sprinkled, ar.d rolled with a horse roller of 150 pounds per inch run. 
The one-inch stone and scfeenings were then spread, sprinkled, and rolled 
with a steam roller of about 400 pounds per inch run. 

After the rolhng was partially completed the passing traffic was allowed 
upon it, and any large stones that came to the surface, as well as all 
small stones that failed to bind, were raked off and sent back to the 
crusher to be re-broken for screenings. No water-worn or other rounded 
stones were allowed m the work. Advantage was taken of every rainfall 
to roll the surface of the road, because we found that it could be com- 
pacted much more thoroughly in wet than in dry weather. Where the 
pavement was laid in a soft substratum it required nearly double the 
amount of rolling sufficient for a solid foundation. 

The grades of these roads vary from 6>^ feet to 8 inches per 100 feet 
and the crowns vary from 1 2 inches to 8 inches. 

The roads have now been open for traffic about three years ; those 
along the railroad tracks are used by about 600 wagons per day, the 



CONSTRUCTION AND MAINTENANCE OF ROADS. 121 

others by about 400 wagons per day. Fully one half of the traffic on both 
roads consists of heavy beer wagons from the adjoining breweries, stone 
trucks and ice carts, ranging in weight from 3 to 6 tons ; the balance of 
the traffic, of ordinary farm wagons, carriages, etc. 

No especial care has been taken of the roads, except to see that the 
gutters and culverts are kept clean. No ruts have ever appeared, and the 
surface is now smooth and in good condition. In hot weather the roads 
are somewhat dusty, and in long dry spells they will loosen and break up 
in spots, where disturbed by the corked shoes of horses drawing very 
heavy loads, but after the first rain the surface immediately rebinds and 
again becomes perfectly smooth. 

Wind and water are, perhaps, the two greatest enemies of Macadam 
roads ; the wind, by blowmg off the slight dust which naturally accumulates 
on the surface, removes from the road the cushion, which is not only a 
relief to the traveler, but which also preserves the metal of the road from 
a vast amount of wear and tear; the water, by flooding the road, has 
sometimes the same effect as the wind, and if by any means the surface 
of the road is exposed to a running stream the stones are sure to loosen. 

The only effectual remedy we found was to ra'se the crown of the road 
sufficiently to shed the water quickly into the gutters, and to keep the 
road sprinkled, so that when the winds and floods came the surface would 
be smooth and compact and not liable to their disintegrating influences. 

On the roads by the side of the horse railroad tracks the wear has been 
about an inch and a half during these three years, while on the roads free 
from these tracks the wear has been about one inch on the crown and 
perhaps a half inch on the sides. 

The cash cost of the Telford pavement laid under our direction in 1875- 
76 was ninety cents per square yard. 

The stone was broken by a ten-inch " Blake" stone crusher at the rate 
of about twenty cubic yards in ten hours. The size of the stones as they 
came from the crusher was : 50 per cent., 2 inches size ; 25 per cent., \yi 
to I inch size , 25 per cent., screenings and pea dust. 

The cost of the crusher, engine, boiler, &c., set up complete, was about 
$2,500. 

The cost of working per' day, independent of the original cost of the 
machinery and interest thereon, and also independent of any royalty on 
the stone, was found by the contractor to be as follows : 

Kcpairs, lubricants, wear and tear on crusher and enorine, about $ '.00 

1 Engineer, |'2 .50 ; 1 feeder, $1.50; 1 screener, .^1.5u ; 5 laborers quarrying and bieakiig 

111) stones at $1.00 . 10. "50 

1 team hauling scone 6.00 

1 Coalhalfton ....* .'..".....*.. 2.50 



Cost of preparing and crushing 20 cubic yards of 6tone S24.00 

Cost of I cubic yard, $1.20. 



122 CONSTRUCTION AND MAINTENANCE OF ROADS. 

The roads built under our direction in 1878, and now building, are the 
same in every particular as those built in 1875-76, except that they occupy 
only 20 feet in width of the crown of the road ; the steam roller was not 
used, and as it is very difficult to obtain an abundant supply of water in 
the locality, we have to rely on the rainfall for sprinkling, and do all our 
rolling in wet weather. A horse roller is used of 150 pounds per inch run. 

Some 3,000 square yards of these roads were completed one year ago, 
and have been, since that time, subjected to a daily traffic of about 150 
wagons, principally carts, loaded with stone and dirt. The surface of the 
pavement is now as nearly perfect as it is possible to imagine that of a 
macadamized road to be. 

The cash cost of these roads is eighty cents per square yard. 

-^ CONCLUSIONS. 

A Telford road m^y be practically divided into two parts. 

1. The foundation, which should be uniformly secure, and which 
should be at the same time a perfect blind drain. 

2. The superstructure, which should be a durable, water-tight roof. 

If these conditions are complied with — if proper materials are used in 
the construction of the road, and reasonable attention is given to its main- 
tenance, the result will be as has been claimed, a durable road, unsur- 
passed for comfort of travel, and one to be preferred to all others for sani- 
tary reasons. 

If these conditions are not attended to the road will last but a short 
time. 

The foundation is of the first importance. It should be eight inches in 
depth. More than this is a waste of material, and a less depth is not suf- 
ficiently secure for want of proper bond. It must be laid as close as pos- 
sible by hand, then the interstices at the top wedged and sledged, until 
the small stones that compose the superstructure cannot work down, and 
fill the interstices at the bottom of the foundation. 

Too much emphasis cannot be given to this part of the work. It is 
not only essential to perfect sub- drainage ; it is equally important in the 
great saving of the cost of building the road. A loose foundation, which 
allows the small stones to settle down upon the large ones, will require 
nearly as many again of the small stones before a proper surface can be 
obtained, hence the cost of the superstructure will be nearly doubled. Of 
course, if the small stones work down among the large stones, the latter 
will work up the surface, and ultimately ruin the road. 

An excellent test of a foundation, when the substratum is firm, is to 
drive a loaded truck — weighing about three tons — over the pavement be- 
fore any of the upper courses are placed thereon ; if the foundation has 
been properly laid no ruts or other displacement will occur. 



CONSTRUCTION AND MAINTENANCE OF ROADS, 123 

As to the size of the foundation stones, we prefer them large rather 
than small. Nothing is so dangerous as thin slabs. A large stone now 
and then, say ten inches wide, well bedded, seems to act as an anchor 
for the rest, and we have yet to find an instance where the small stones 
have broken loose from suci a foundation stone. 

In regard to the superstructure, we are convinced that if the material 
is crushed trap, any increase over four inches in depth is a waste of 
material. We found this to be the most expensive portion of the road, 
the cost of the eight-inch foundation being to the cost of the four-inch 
superstructure as one is to two. Four inches will answer all requirements 
as well as any greater depth, because after the metal has worn down two 
inches, the road, owing to unequal wear, will need to have a new coating 
in any event, and the amount saved in the first cost and the interest 
thereon, by making the superstructure only four inches deep, will keep 
the road in repair for many years. 

In regard to steam rolling, it is often questionable whether it is 
essential, or even desirable, in the building of Macadamized roads, espe- 
cially when the road is built of New Jersey trap rock. 

The principal action of the steam roller is to crush the stone into the 
crevices, and the result is, that a crust is quickly formed. On the other 
hand, the horse roller rattles around and shakes the small stones about, 
until they are firmly bedded upon the rough but firm foundation and 
upon each other. No crust is formed, but, on the contrary, a compact 
homogeneous mass, which result is much more to be desired. Ay^ain, 
the road bed upon which the pavement is laid often varies very greatly ; 
frequently a rocky bottom adjoins a soft stratum; on one side of the road 
may be an excavation and the other side a fill. In such a case, a heavy 
roller is much more likely to disturb the uniformity of the foundation 
than a lighter one, no matter how great care may have been taken to 
provide for emergency. 

If it be necessary to finish the surface of the pavement within a week 
or two, a steam roller must certainly be used, but we believe that rapidly 
made roads are much less durable than those whose construction extends 
over a long period of time. 

It required at least three months to finally form the surface of the 
roads built by us in 1875-76, while on the roads now building, some of 
the sections have required as much as six months. In the meantime, the 
surface is kept free from loose and rolling stones, so that there is no 
brutal pulling through the road metal. 

After a road has been slowly compacted in this way, we believe the 
surface will be found much more durable than that of any rapidly made 
steam rolled road. 

As to "bindiag," our experience has been that during the construction 



124 CONSTRUCTION AND MAINTENANCE OF ROADS. 

of the road the less foreign material used the better, unless, perhaps, 
along the edges of pavement which has only an earth support. In such 
a case, it is necessary to bind the edges as quickly as possible, in order to 
prevent the sides of the road from spreading while the surface is forming. 
After that is accomplished, very little wear comes on the extreme edges of 
the road. 

As an aid in the rapid formation of a fine surface, a little yellow clay 
placed just below the upper course is almost invaluable, but when the 
crust is broken the danger is that the surface will soon disintegrate, while 
if, instead of the clay, stone dust is placed between the courses of broken 
stone, and a top dressmg one inch deep of screenings, such as are pre- 
sented herewith, is spread over the surface and is thoroughly worked into 
the broken stones, the surface is equally fine and much more durable; if 
a spot does loosen here and there, it does not spread and a little moisture 
quickly rebinds the loosened stones. 

Finally, as to the stones for the superstructure, we greatly prefer 
machine-crushed to hand-broken stones. 

1. Because they are much more uniform in size, each having actually 
passed through a revolving screen. 

2. Because the edges of the stones are much rharper and bind better. 

3. Because from the machine alone can we obtain the screenmgs and 
detritus which we consider so essential for compacting the road and for 
satisfactory top dressing. 

— George D. Ansley. — My experience is decidedly in favor of steam 
rolled Macadam or Telford roads over those formed by horse roller ; in 
fact. I have altogether given up the use of the latter, and employ a 15-ton 
Aveiing & Porter, the result being far greater economy in the end as to 
outlay, and a decidedly smoother and more permanent surface is obtained. 

As to compacting with traffic, I am altogether opposed to it, as being 
inhuman toward horses and extravagant in the waste of material. I speak 
of the case when any considerable extent of roadway is to be covered ; 
but ill small repairs, or what is technically called " darning," I first pick 
up the margins of the depressions to the depth of an inch or two, and 
then flush up with stone broken to pass through a 2-inch ring ; the edges 
of the patch are then covered with road grit, obtained at hand and pounded 
with a rammer. In these repairs it is found that the horses feet avoid 
the fresh stone, while the wheels of the vehicles run over the patch and 
compact it gradually from the edges to the centre and a very good "mend" 
is thus made. 

In reading over Mr. North's valuable collection of short histories of 
road making, I was particularly attracted by the mention of ramming, on 
page 103. There is a short mention of a rammer 8 inches diameter, 
weighing 70 pounds. Although steam rollers are far more satisfactory 



CONSTRUCTION AND MAINTENANCE OF ROADS. 125 

than horse rollers, it seems to me that a s'ill further improvement may be 
made by the more general introduction of the rammer. In all cases of 
roads, whether Telford or Macadam, or stone paving, or wood paving, the 
first imperfections are the same ; the surface may not be worn away 
materially, but there are depressions or concavities that hold water. Our 
block stone pavements get into bad order chiefly through unevenness, and 
a heavy expense is incurred in repairs, while the hollow parts are found to 
be hard and well set, and the blocks not worn, perhaps, any more than 
those forming the better parts of the road. A wooden pavement on one 
of our streets was condemned for being in hills and hollows ; although 
incidentally there were rotten blocks that broomed and wore away, it was 
found, on taking it up, that the foundation was uneven, and this notwith- 
standing that it had been steam-rolled before the blocks were laid on, five 
years before. All this tells the same tale — the earthy foundation is of un- 
equal density. 

Much more attention has been paid to the coating of stone or other 
material than to the lowest or earth foundation. When a new road is 
made, the proper form may be given to the earth foundation, and it may 
be steam rolled ; inequalities then showing themselves may be flushed up 
and re-rolled, but a roller will bridge over smaller soft places which still 
remain unseen until the road is completed and heavy traffic put upon it, 
and then we have saucer- like dips in its surface, to be repaired within a 
short time after the road is made ; and although the specification may 
require that these repairs shall be done by the contractor, the surface 
being thus broken, the road is never so good afterward as it would be if 
undisturbed. 

How the rammer which Mr. North refers to was used is not mentioned ; 
but if by steam power, it might be neither expensive nor slow. 

I am inclined to think that the regular stroke of a rammer is the only 
method of producing equal densities for roads, as well as for other pur- 
poses, and that the most important part of road making for its application 
is the earthy bottom. 

After the ramming to equal density, I cannot see that Telford's method 
is better than Macadam's for general adoption; local circumstances, 
however, would decide in each case. 

After reading through all the various descriptions, and adding my 
own views from observation and experience, I consider the object to be 
aimed at is as near as possible, a solid bed of stone. This certainly can- 
not be accomplished by putting on any earthy matter as binding. Broken 
stone in thin layers, 3 to 4 inches, chinked with fine chippings or screen- 
ings until full, and then watered and rolled with steam roller, will come 
very near the desideratum. Of course the lower strata may be of stone, 
less hard than the top. The size of broken stone for the upper part is 



126 CONSTRUCTION AND MAINTENANCE OF ROADS. 

important. A 2}4''inch ring allows stone of considerable size to be mixed 
with lesser ones, and it is these larger ones that first get loose and move 
about on the surface. For the surface coating I prefer hand broken stone 
over machine broken, as the form is generally more cubical and less apt 
to become disintegrated. 

Gravel is much more difficult to reduce to solidity than broken stone; 
but where there is a large supply, and cheap, it is well to follow the 
principle before mentioned. The gravel should be screened, and the 
coarser sort laid on first and then chinked up with the finer. If this is 
done, and all coarse gravel kept away from the top coating, water and 
steam rolling will make a good road in almost any case without earthy 
binding. Earth matter works into mud, and should be avoided, unless 
the gravel is so round and movable that nothing else will keep it quiet. 

Where old paving is taken up, and it is proposed to put down 
Macadam, I consider that there is the same necessity for testing the 
density of the foundation, and rendering it equal by ramming. 

A. B. Hill. — In New Haven we have tried several plans in regard to 
the binding material of the Telford pavement. Using an inch of loam 
on the crushed stone, with two inches of screenings over that ; also using 
sand instead of the loam ; but the best results with us are obtained by 
using the trap rock screenings alone, spread on in thin layers, sprinkled 
and roughly rolled. This makes a very sohd, firm surface, which does 
not wear into ruts as soon as the pavements are top-dressed by the other 
methods. The roller used is the 15-ton Aveling & Porter. 

As the grades in New Haven are generally very light, and it is desira- 
ble to secure a uniform, smooth gutter, the latter is made of blue stone, 
12 inches wide and not less than 4 inches thick, bedded in sand next to 
the curb, closely jointed, well rammed, and, after the pavement is com- 
plete, thoroughly grouted. 

A space of three feet outside the gutter stone, between the rails of the 
horse railroad tracks, and for three or four feet outside the rails, is laid 
with stone blocks. 

The Telford pavement is 16 inches thick at the centre and 14 at the 
sides, made up of 4 courses of trap rock ; the first or bottom course 7 
inches thick at the centre and 5 inches at the sides ; the stones of the size 
and placed as usually specified for Telford foundation ; the second course, 
3 inches thick, of stone simply raked out and sorted at the foot of the 
trap dikes (not " broken " or " crushed "), varying in largest dimensions 
from I inch to 4 inches, spread on the first course and rolled until solid ; 
the third course, 4 inches thick of " crushed " stone, also rolled ; 
the fourth course, or top-dressing, about 2 inches thick of screenings, 
spread on in three layers, each layer sprinkled and thoroughly rolled 
in. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 127 

The averag:e cost of the Telford pavement in New Haven, including 
the Belgian blocks, blue stone gutters, crosswalks, inspecting, rolling, &c., 
was, for 1876, $1.18 per square yard. 
'• 1877, 1.05 
" 1878, 1. 15 

E. Lavoinne, Engineer des Fonts et Chaussees (through the Secre- 
tary). — The criticism of Mr. North upon the Macadam roads in the City 
of Paris is to the effect that owing to the method of compacting, suffi- 
cient stability is not given to the stones to resist the traffic. Mr. Malo is 
quoted as sustaining this criticism. Even if the bad results in Macadam 
pavement in Paris were something like what Mr. Malo describes in his 
rather sweeping remarks, the fair inference would be, it seems to me, that 
the system of construction was not the best m that location on account of 
the heavy traffic. 

Macadam roads when introduced in Paris to replace the former pave- 
ments were considered by many engineers as a blunder, on account of the 
cost of their maintenance and other peculiarities. It is certain that no 
Macadam road, even if constructed under the best conditions, could stand 
the enormous traffic existing in many streets, which is not occasional, as 
Mr. North states is the case for some of the Boulevards of New York, but 
continuous and daily for most of them. 

As regards the construction of roads, the illustration of what Mr. 
North ca'ls the French system, such as he saw applied in the repairs of 
some streets in Paris, hardly gives an exact idea of the standard system 
adopted by many French engineers. They generally consider that in a 
perfect Macadam all stones should bear directly against one another by 
faces as large as possible, not by edges, and that the interstices, previously 
reduced to a minimum by rolling, should be filled afterwards with a bind- 
ing which cannot be affected by atmospheric influence nor give access to 
moisture. Thus far they agree with Mr. North — but they disagree with 
him as to what is the best binding. 

Instead of screenings or very small stones with the addition of dust 
and water, they prefer to use sand with a small quantity of chalky dust 
employed when compacting is at an end. They consider, contrary to 
Mr. North's theory, that when the stones, whose sizes vary between 1% 
and 2>^ inches, have been thoroughly packed together by rolling before 
any addition of binding, so that they move no more under the roller, and 
a beginning of crushing takes place, then an addition of smaller stones is 
useless for stability ; if very small stones like screenings were then added, 
they would be crushed and produce an excess of dust injurious to general 
stability. Sand, injected by thorough watering between the stones is 
not liable to that objection, since, filling all the interstices, it tends to 
equalize the pressures between the stones. The addition of chalky dust 



128 CONSTRUCTION AND MAINTENANCE OF ROADS. 

diluted by water, at the end of the operation, fills the interstices between 
the grains of sand making with it a sort of mortar and coating for the 
surface. In my own experience the best results followed this method ; 
the consolidation of the Macadam was very satisfactory at the end, rolling 
not being spared before the addition of binding. Loose stones occurred 
only at a few points. 

It may be that the roads examined by Mr. North, in Paris, were con- 
structed in too thick layers and too hastily permit the stones, prior to any 
addition of binding, to have the required stabihty, much rolling being 
necessary for this result. This may be the reason why loose stones were 
seen. If the stones have not been packed and wedged previously by 
thorough rolling, we cannot expect binding to make them immediately 
compact. 

The system mentioned as used in New York (St. Nicholas Avenue), 
in which stones of from i to i}4 mches are employed for he top course, 
will, no doubt, do for light travel (light, not heavy carriages) ; but such 
pavement would very likely be destroyed by a heavy traffic, as the small 
stones would then be rapidly ground and disintegrated. From my own 
experience and that of many engineers in France, I am fully satisfied that 
the capital difference between the roads in the old Macadam style without 
rolling, and those that are rolled, whether with steam or horse power, is 
the degree of internal wear ; as the grinding of the stones by their recip- 
rocal friction or internal disintegration is much more rapid under heavy 
traffic with the former than the latter. In the first case the proportion of 
disintegrated material, detritus, to the stone is generally large after a short 
time ; very small in the second if proper care has been given to the work. 

Evidently much more consideration should be given to the internal 
wearing, which is of serious consequence as to cost of maintenance, than 
to the incomplete consolidation of the road immediately after rolling, 
which could be remedied by more rolling or made up afterward by the 
traffic itself and by removing the excess of binding material by sweeping. 

In conclusion, it is suggested that for a fair comparison between the 
different systems of constructing the roads, there should be taken into 
account both the quantity and quality of the traffic, and also the cost of 
maintenance under the same conditions for a fixed period. Conclusions 
might be different if full consideration were given to these points. 

E. B. Van Winkle. — I would say that I am familiar with the roads 
Mr. North has been constructing for the past few years ; that is, with their 
present condition, and should like to ask Mr. North if their present condi- 
tion bears any relation to the amount of rolling he put upon them ; for in- 
stance, the Southern Boulevard, which I now consider to be the best of 
these roads, and the one that carries the greatest traffic, did that receive 
the greatest amount of rolling ? 

n 



COXSTRUCTION AND MAINTENANCE OF ROADS. 129 

E. P. North. — The Southern Boulevard received 0.859 ^o"^ "^i^^ P^** 
square yard, or 5.177 ton miles per cubic yard, which is more rolling than 
any other road constructed by me had, and more than any road known to 
me has had applied to it. 

The road has stood the wear very well, though part of it is exposed to 
a very constant breeze from the Sound, which deprives it of the protection 
that a layer of dust would afford. 

The teams on it were counted from 8 a. m. to 5 p. m., and averaged 
about 300, from four-horse teams, with six or seven tons to the load, to 
buggies. 

E. B. Van Winkle. — Next to the Southern Boulevard I should place 
the streets constructed by Mr. North in the following order as to degree 
of excellence, always judging by their present condition : 

1st. One Hundred and Thirty-eighth street; 2d. One Hundred and 
Sixty-seventh street ; and last, Mott avenue. Please, if possible, state 
which of these received the greatest amount of rolling, and if there were 
any difference in the quality and size of the metal and the material used 
for binding. 

E. P. North. — One Hundred and Thirty-eighth street, which has two 
courses of broken stone, each about 6 inches deep before rolling, received 
less rolling than the Southern Boulevard ; the surface is satisfactory ex- 
cept in one place, where the bottom was bad and mud worked up through 
the metal where there are some loose stones. One Hundred and Sixty- 
seventh street is on a heavy grade, part being at the rate of 11 2-10 feet 
per 100, and the rest with 8 per 100 for a maximum. The first was rolled 
with both horse and steam rollers, the steam roller ascending by an easier 
grade. Some clay hardpan was used here in connection with the screen- 
ings, both 10 increase the adhesion of the roller wheels and facilitate the 
compacting of the road bed. The roller, a 15-ton Aveling & Porter, old 
pattern, ascended the grade after the application of the hardpan. On the 
lighter grades nothing but screenings was used for binding, and the rolling 
was done entirely by steam. This part of the wheelway wears much bet- 
ter than that portion where hardpan was used. No reliable account was 
kept of the amount of rolling this street received. 

The circumstances under which the wheelway on Mott avenue was 
constructed are fully detailed in Transactions, Vol. VHI., page no (May, 
1879). On account of its treacherous bottom it probably received less 
rolling per square yard that any other road, though it was impossible to 
keep accounts of the amount of rolling done. 

All of these streets are Macadamized with two-inch trap and clean trap 
screenings, excepting that portion of One Hundred and Sixty-seventh 
street mentioned above. 

B. F. Morse. — The paving of the Cleveland Viaduct, west of the 



I30 CONSTRUCTION AND MAINTENANCE OF ROADS. 

river, over the arches, is laid with New York Medina sandstone ; the road- 
way is 42 feet between curbstones, with a double track street railroad in 
the centre. 

The ballast used was of the best quality of bank gravel spread in layers 
of about five inches in depth. Each layer was sprinkled with wa^er and 
rolled. The last layer, or that directly underneath the stone, was about 
two inches deep, and was left without sprinkling or rolling to receive the 
bed of the paving stones. The surface of the ballasting was finished to 
the true crown of the roadway. 

The pavement is laid with blocks, dressed nearly parallel on top and 
bottom, sides and ends, laid in courses transversely across the roadway. 
The courses were from three to four inches thick, and from six to seven 
inches in depth, and the stone from seven to twelve inches in length 
The stones were set close together, so that no joint was more than one- 
half inch open for at least two and one-half inches down from the top 
surface. 

No gravel or sand was placed between or on top of the pavement 
while it was being laid. After the stones had been set in place in sections 
of fifty to one hundred feet in length of the street a light top dressing of 
gravel or sand was spread over the surface and swept into the joints with 
a steel splint broom. The pavement was then thoroughly sprinkled or 
flooded with water. Then the pavement was thoroughly rammed two or 
more times with a paver's rammer weighing about ninety pounds ; then 
the pavement was again washed or flooded and allowed to dry off. 

The joints were then filled to a depth of three to five inches with a 
concrete composed of Trinidad bitumen and coal-tar cement, distilled at a 
temperature of not less than 600 degrees Fahrenheit, and mixed in proper 
proportion, so as not to soften or become brittle under heat or cold, and 
was poured into the joints of the pavement at a temperature of not less 
than 300 degrees, and then the whole surface was covered with one-half 
inch of fine gravel or sand, which completed the work. 

The pavement on the fixed iron spans was laid in the following manner : 
Strips of oak plank, varying in thickness from one and a half to three inches, 
were secured to the iron floor beams, running longitudinally, to give the 
proper crown to the roadway. On top of these longitudinal floor beams 
was laid a layer of two and one-half inch plank, joints well broken and 
spiked down. On top of this layer of plank there was laid two thicknesses 
of tarred roofing felt, or paper, laid in hot roofing cement, and the whole 
covered with one-fourth of an inch of plastic pitch, and over this was laid 
.1 layer of inch boards or sheathings, breaking joints with the plank under- 
neath, and thoroughly spiked down. 

The paving is what is usually called "Nicholson," and consists of blocks 
four inches long and three inches thick laid upon and in rows across the 



CONSTRUCTION AND MAINTENANCE OF ROADS. 131 

roadway, with a three-fourth-inch strip, one and one-half inches in depth 
between the rows of blocks, and nailed to the flooring, the blocks breakings 
joints at least two inches with adjoining row. The space between the 
rows of blocks was then filled with concrete, composed of one part of hot 
undistilled gas tar to two parts of pitch, mixed with clean lake sand and 
fine gravel, applied hot and driven into the joints with an iron blade and 
heavy rammer until the spaces were even full. The whole surface of the 
paving and gutters was then coated with a top dressing of coal tar pitch 
and fine gravel, rolled thoroughly with a heavy hand roller. The best 
quality of seasoned white oak was used for all the wood parts of the pave- 
ment and plank floors. 

E. S. Chesbrough. — I cannot state the average wear of wood pave- 
ments ; I can only state that it differs very much with regard to different 
kinds and in different localities. You can easily see that very much depends 
upon the faithfulness of doing the work and the material used. 

In some cases in Chicago wooden pavements have lasted ten years, 
and even longer ; and in others they have become very rough and uneven 
in three or four years. I am not able to give the precise average, but of 
course a great deal depends upon the traffic. In the river tunnels the 
wooden pavements have worn out in less than two years, and where the 
wheels were confined very much to the same tracks they m.ake ruts in 
a short time. In other cases, where the streets are broad and clear, and 
the traffic is spread over a large space, they have lasted a long time ; in 
some cases ten years. It is impossible to give the rule in regard to that 
unless you take into account various circumstances. 

Edward R. Andrews. — I would like to ask Mr. Chesbrough whether 
at Chicago there is any very perceptible wear in wooden pavements until 
decay sets in } 

Edward S. Chesbrough. — Decidedly ; I have seen some worn 
down more than two inches without any apparent decay. 

Edward R. Andrews. — Mr. North states that a well made Macadam 
road, constructed with trap rock, is, after an earth road, the pleasantest 
and safest known. But trap rock or other really good materials for making 
Macadam roads are not available everywhere, and, at best. Macadam roads 
are only adapted for pleasure travel in parks or suburban towns, where 
they can be constantly watered and never allowed to get out of repair. 
Macadam is not adapted for general use in cities. Under heavy traffic 
the surface is constantly ground into powder, which rises in dust in the 
summer, and they are very muddy in the winter. Even in Paris, where 
the maintenance is most thorough, the streets being continually watered 
in summer in the manner described by Mr. North, and frequently washed 
after a day of unusual wear, and scraped by a large army of cantonniers, 
yet, after heavy rains, the mud is frequently nearly ankle deep, and in very 



132 CONSTRUCTION AND MAINTENANCE OF ROADS. 

hot weather, during the intervals of watering, or in frosty weather, the air is 
filled with most penetrating dust. Mr. Flad describes the same state of 
things in St Louis ; and in Boston, when, in winter, there is no snow to cover 
the ground, and, on account of the cold, the streets cannot be watered, the 
dust is intolerable ; and in summer, where, for economy's sake, watering 
is neglected, a large part of the material with which the roads are made is 
blown into the sea. 

The compressed asphalte, so common in London and Paris, when con- 
structed as thoroughly as it is in those cities, and as that on Fifth Avenue, 
in front of the Hotel Brunswick, has been, is a most excellent pavement, 
but it also demands the most careful maintenance. No dirt should be 
allowed to accumulate upon it. In frosty or in damp weather coarse sand 
or fine gravel should be spread over the surface to give a good footing for 
horses— this is done abroad — and then it is not slippery. It is very quiet, 
and, in fact, has almost all the qualities needed in a perfect pavement ; 
but it can only be laid on levels, and is expensive. 

Stone Block Pavements are in many parts of the country the cheapest 
and possibly may be the best where the traffic is very heavy, but it is 
emphatically the worst pavement for streets of residences or wherever 
quiet is desirable ; and there is no question but that if the incessant din 
from the rattling of omnibuses, heavy teams, milk wagons, &c., from 
which one suffers in large cities paved with stone blocks, could be dis- 
pensed with by adopting a quiet pavement, the length of life of citizens 
would be increased and the general health improved. Such would have 
been the case long ago in New York, had it not been that the wooden 
pavements . laid during the " Tweed " days were such evident jobs. In 
London, wooden pavements give entire satisfaction. The earliest were 
not quite successful, but the defects in construction have been remedied, 
and now broad areas of heavily worked streets previously paved with stone 
are being laid with wooden blocks, which are found to wear satisfactorily. 

In the West, where stone for pavements cannot be had, wooden blocks 
are largely used ; but, as wood is cheap and can be replaced without much 
expense, no sound principles are followed in their construction. In the 
Eastern States, no one will allow that a wooden pavement can be good 
except when newly laid, when all agree that it is delightful. There seems 
to be an unwillingness, even among engineers, to give the subject the at- 
tention it deserves. All agree that stone pavements are a curse, and that 
it would be a blessing if a good substitute could be found, but because 
wooden pavements, as they have been made here, have not been a suc- 
cess, condemn them as a class. 

Mr. North has stated what has been the general practice in laying 
wooden pavements in this country. Many methods have been tried, but 
they have almost without exception been " laid ^'x'&s. green or wet blocks, 



CONSTRUCTIOiY AND MAINTENANCE OE ROADS. 133 

more or less thoroughly dipped in tar, on a bed of sand, not always well 
rammed, with or without the interposition of a tarred pine board, with 
transverse joints from one to one and a half inches wide filled with gravel 
and coal tar," and I might add, the whole done in a most unworkmanlike 
manner. 

The results are what might have been expected. The careless manner 
in which the joints have been filled, has left many channels open for the 
admission of water, which undermines the sand foundation, so that there 
is an uneven subsidence under the passing wheels, and holes, small at 
first, but daily growing larger, appear, so that the surface is soon destroyed. 
The result is but little better when tarred boards are laid under the blocks. 
This practice of tarring wet sappy boards and blocks seems to be an in- 
vention to make them decay as soon as possible. It closes up the cells of 
the wood, so that the moisture cannot escape ; fermentation immediately 
follows, which quickly destroys the strength of the fibres and reduces them 
to punk. A pavement, constructed in this manner, would fail, of course. 
Thoroughly seasoned wood might be benefited by the tarring process, 
but green wood never. 

Observe how differently wooden pavements are constructed in Lon- 
don. Mr. North describes several methods, either of which is vastly supe- 
rior to any of the patented systems used here. A rigid foundation of 
bituminous or cement concrete is universal. This costs more than sand, 
but it is permanent, and will prevent the blocks from sinking under the 
wheels. English engineers, in discussing pavements, call the foundation 
the true pavement, the blocks being the wearing surface only. The 
" Henson " pavement, with some modifications, strongly recommends 
itself to my mind as the best for this country. Instead of a layer of tarred 
paper on the concrete, I would use a thin layer of pitch, with oil enough 
in it to make it permanently slightly plastic, setting the blocks upon it 
while hot and soft, using the strips of tarred felt between the rows, and 
driving the blocks together as described by Mr. North. The tarred felt 
would make a very close joint. Then pour melted pitch over the whole 
surface, taking care to fill every crevice, and upon this spread fine sharp 
gravel, which will work into the ends of the blocks and form a surface 
resembling macadam, and afford a far better footing than wide spaces be- 
tween the rows, which serve as receptacles for mud and dust. It is easy 
to keep this pavement clean. No water can penetrate it, so that it will 
not be injured by frost. The blocks themselves, if creosoted, will not 
absorb water, and if laid without spaces between the blocks, the drainage 
will be surface drainage solely, which is of the first importance. 

But the pavement would be short-lived, if green and wet blocks are 
used. It is not practicable to use, as Mr. North says is the case in Lon- 
don, " wood better seasoned than the pine generally used by house car- 



134 CONSTRUCTION AND MAINTENANCE OF ROADS. 

penters in this country." Seasoned wood cannot be obtained in sufficient 
quantities here. But, what is far better, it can be preserved from decay, 
I have no faith in any method of wood preservation for paving blocks 
which does not exclude water. The blocks are so short, that any soluble 
preparation is quickly washed out of them, and, if not made waterproof, 
they are certain to absorb the seeds of destruction from the filth in the 
streets. The blocks should be well saturated with creosote oil, whose 
chemical constituents act preservatively upon the. fibres of the wood, by 
coagulating the albumen of the sap, while the fatty matters act mechan- 
ically in obstructing the pores of the wood and keep the water out. At 
the same time, as oil cannot be injected into wood full of moisture, the 
thorough artificial seasoning, which forms a part of the process of creo- 
soting as carried on in this country, is as useful to the timber as any of 
the metallic salt processes. 

By thoroughly creosoting the blocks, expansion and consequent throw- 
ing out of the blocks is prevented. They wall not shrmk or expand. 
The wood is also rendered homogeneous, the sap wood becoming as 
durable as heart wood. Looking to sanitary considerations, the 
creosoted wooden pavement is perfect. The carbolic acid contained in 
the oil is a powerful disinfectant, and as the pavement described will not 
absorb any deleterious substance from the surface, it has only to be kept 
clean to maintain the best sanitary condition. This is far from being 
the case with wooden pavements laid on the American plan. They soon 
become a mass of decaying vegetable matter, and, as their powers of 
absorption increases with their disintegration, they become filled with 
corruptible matter absorbed from the filth of the street, and as their sur- 
face becomes filled with holes, it is absolutely impossible to keep them 
properly clean. 

A good wooden pavement is also an inexpensive one. The cost, includ- 
ing a cement concrete foundation, 6 inches deep, would not exceed $3.00 
per square yard. The system of maintenance adopted in London, of making 
it a part of the contract of construction, would insure good workmanship 
in laying the pavement, and a good permanent roadway afterwards. It 
would not be difficult to find responsible and honest contractors willing to 
take such a contract at a fair price. 

In considering this subject, one should not overlook the statistics of 
accidents gathered in London by Col. Haywood,* which show that a 
London horse will travel on granite 132 miles, on asphalte 191, and on 
wood 446 miles, before an accident occurs. 

The actual wear of wooden blocks is very slight, as long as the fibres 
of the wood are sound. Mr. North states that it is yi of an inch per 

* See full reports in the library of the Society. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 135 

annum in the streets in London, with the heaviest traffic. Mr. Geo. 
Frederick Deacon, Member Inst. C. E., in a paper read before the Inst, 
of C. E., states that, in Great Howard street, Liverpool, which is a shop 
street, with a traffic consisting chiefly of carriages, amounting to about 
94,000 tons per annum per yard in width, the pavement was worn to the 
extent of* >^ of an inch in four years. This would give a life of nearly 
twenty years before the blocks would be reduced from 6 iHches to a 
thickness of 3 inches, which is still sufficient to maintain the blocks in 
place. 

In Oxford street, in London, where the traffic is equal to 300 tons per 
foot per day, the amount of wear has been found to be from xV to ^ inch 
during three and a half years. This street is laid with the Henson pave- 
ment. This slight wear is largely due to the fact that the ends of the 
fibres do not broom, and thus retain their original strength. 

C. Shaler Smith. — I merely wish to ask Mr. Andrews — speaking 
of the foundations of wooden pavements — if he is aware of any pavement 
being laid as upon the Cleveland Viaduct, that is, Nicholson pavement 
upon an iron foundation ? 

E. R. Andrews. — I am not aware of any except the Broadway Bridge 
in South Boston, where it was necessary to have a light pavement. A 
bituminous concrete about two inches thick was spread on the top sheet- 
ing and allowed to become solid ; then a thin coating of hot tar spread 
evenly, and creosoted spruce blocks, injected at my works wiih 12 lbs. of 
oil per cubic foot laid in rows yi inch apart, and the interstices filled with 
pitch and the surface spread with gravel. 

G. BousCAREN. — Can you give the cost of.creosotmg .'' 

E. R. Andrews. — $12.00 to $16.00 per thousand feet, board measure. 

G. Bouscaren. — Can spruce be treated well } 

E. R. Andrews. — Spruce does not absorb oil readily on account of 
the compact character of its fibres, yet it will take in a gallon of oil per 
cubic foot ; hemlock, pine, both white and yellow, and porous oak, are 
more absorbent. Wood which is the most destructible, because it ab- 
sorbs water readily, is really the best for creosoting, as, for instance, the 
gums and cottonwood. 

G. Bouscaren. — Have you any special rule for determining the 
amount of carbolic acid in the oil ? 

E. R. Andrews. — I have not taken any pains to ascertain. The 
quantity depends upon the character of the coal from which the gas was 
made, varying from 5 to 10 per cent. It has been ascertamed, however 
through careful experiments by a Belgian chemist, that the wood-preserv- 
ing qualities of creosote oil are due rather to the water-proofing imparted 
to the wood by the hydro-carbons contained in it than by the carbolic acid. 
The latter is very volatile, and were it not retained by the gummy, resinous 



136 CONSTRUCTION AND MAINTENANCE OF ROADS. 

oil, would quickly escape into the air. In England ho reference is made to 
the quantity of carbolic acid contained in dead-oil to be used in the speci- 
fications for contract work. Carefully conducted experiments of my own 
with pieces of yellow pine, 8 inches by 8 inches and 9 feet long, have 
shown that six months after treatment they did not absorb any water dur- 
ing a soaking of 48 hours under water. 

M. Meriwether. — We made in Memphis, in 1867, what has proved 
to us a very costly experiment in wooden pavements. We laid there in 
that year and the succeedmg spring some 225,000 square yards of what is 
known as Nicholson pavement. The streets on which this was laid rise 
six inches from the side to the centre of the street. Two inches to two 
and a half of sand were laid down, and that covered over with an inch 
board longitudinally. Those boards were immersed in hot coal-tar. 
After that were laid cypress blocks eight to twelve inches long, with a 
thickness of three inches, with a cleat between them, tacked to them. 
About one-half of that kind were immersed in boiling tar. According to 
the contract it was to be red cypress wood, which is very durable above- 
ground, and of more than ordinary durability underground, and is found 
to last better than ordinary oak ; but the sap portion of that wood is very 
perishable, rotting within one or two years if exposed above-ground. The 
heart will last twenty-five years, or so, in fences. I mention this to show 
the durability of the material. Most of that was entirely covered with 
boiling coal-tar and small gravel, and the interstices filled with sand, mak- 
ing a beautiful pavement for about three or four years. Some portions of 
it, however, began to show decay in three years, where the sap of the 
block was put in. The contractor got in a good many sap blocks, and as 
soon as they began to decay the adjacent blocks were loosened, so at the 
end of about five years it was in many places impassable, and some blocks 
were entirely destroyed. The remnants of that wooden pavement of 1867 
and 1868 are now there. The pavement cost us $3.89 per square yard. I 
am satisfied had the blocks all been heart cypress it would have been good 
for perhaps ten years. We have portions of the pavement now where the 
heart of the cypress was used, where there is no surface wear perceivable. 
However, we are satisfied with that experiment, and I do not think we 
will ever put down another square yard of wooden pavement of any sort. 
We are now makmg arrangements to pave with granite. 

E. R. Andrews. — It seems to me very clear that the reason why the 
cypress pavement did not last was because the blocks were dipped in tar. 
It is not at all probable that these blocks were perfectly seasoned, because 
seasoned lumber cannot be found in this country for paving purposes, 
hence the sap enclosed within the wood by the tar soon fermented and the 
fibres rapidly decayed. If the blorks had been laid without being dipped 
in tar I think you would have had a very fair pavement now. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 137 

I would like to ask as to the condition of a pavement in Washington 
called the Flannigan pavement, with cypress blocks sawed from round 
sticks and laid promiscuously, large and small together, the spaces 
being filled with pitch. I have understood that that pavement has stood 
well. 

J. E. HiLGARD. — That pavement has done the best of any in the city. 
It was tried as an experiment on Third street, near the railway. 

The city of Washington has made very extensive experiments in the 
matter of wooden pavements. Nothing was done to preserve the blocks. 
They were hemlock ; none of it has lain in tolerable condition over four 
years ; much of it had become intolerable even before that time. I think 
the work was badly done from there not being proper supervision. An 
immense amount of work was undertaken to be done within a limited 
time. It was the most disgraceful failure of wooden pavements ever 
known, and it has been a case of unprecedented decay. None of I he 
streets were in a fit condition to travel over after four years ; most of them 
have been replaced by concrete pavements. With us the experiment has 
been a very expensive one. Climate may have had something to do with 
it, for it is very warm in summer and we have very frequent showers, but 
certamly the decay was unusually rapid. 

E. R. Andrews. — In 1869, Columbus avenue, in Boston, was paved 
with wood ; every one who had any patent pavement was allowed to put 
down a piece ; one section was laid with creosoted blocks, but very imper- 
fectly prepared. All the pavements were taken up and the street repaved 
with the Trinidad bitumen in 1877; but a small delta of the creosoted 
pavement was left, which is still sound and in good condition. 

M. Meriwether. — I did not mention that about one-half of the 
pavement of which I spoke was laid with planks dipped in boiling tar, 
and after making about one-half of it the very difficulty suggested by Mr. 
Andrews arose, and we ceased to immerse the blocks, upon the theory 
that if the under side was covered with tar it would cost more, so they 
stopped that process and laid the balance in the other way, and after the 
planks were down they covered the surface simply with coal tar, upon the 
theory that the bottom of the planks, not being concealed, the acid would 
go down ; but we did not discover that it made any perceptible difference. 
It would probably have been satisfactory if the blocks had been heart 
wood, but the sap of the blocks decaying, led to their destruction by the 
wheels passing over it. It was an utter impossibility to have seasoned 
wood for such an extent of pavement — some 225,000 square yards, hid at 
once. The wood was not in the market, and no one could afford to keep 
such a stock on hand. The result was that the wood was brought di- 
rect^ly from the mills and put down within two or three months from the 
time it was taken from the stump. I do not think any process short of 



138 CONSTRUCTION AND MAINTENANCE OF ROADS. 

thorough seasoning, or some process of drying quickly by steam, would 
do any good. We found it impossible to get the heart cypress entirely, 
and the sap wood would decay in two or three years. 

The blocks covered the surface and prevented the water passing 
down, but it may have passed on the side. They merely covered the 
surface with tar, and some little water might find its way down the side 
of the block. The spaces between the blocks were thoroughly rammed 
with small gravel, with sand with it, and the surface covered with coal 
tar. 

C. Shaler Smith. — I have recently made some experiments for the 
St. Louis Bridge, which illustrate in a marked degree the action of those 
preservatives depending on carbolic acid for their antiseptic value. Find- 
ing the wooden stringers of this structure beginning to rot at the ends and 
other points of support, while the remainder of each stick continued sound 
and untouched by decay, I tried to arrest the rotting by the injection of 
creosote containing ten per cent, of carbolic acid into all these timbers 
which showed signs of decomposing fibre. The effect was remarkable. 
Sound wood was unharmed, but where decay had already commenced the 
acid seized upon the wood and converted all parts affected by rot into a 
brown cinder, in many cases absolutely destroying the bearing value of 
the stick. The experiment was extensively and exhaustively tried, and I 
am satisfied that while creosote is excellent when properly applied to per- 
fectly sound lumber, it will not arrest decay when once started, and in 
many cases will destroy all the unsound parts of a stick. 

And also, that in th^ use of cresote, the proper proportion of carbolic 
acid is a very important element, and should be fixed by specification 
whenever this system of treatment is used. I have likewise continued 
experimenting on other methods of preserving wood, three of which have 
given good results. 

The first is the " Thilmany, old process," This consists in impregnat- 
ing the wood with sulphate of copper, and subsequently with the chloride 
of barium. The chemical action of the two salts fills the pores of the 
wood with the preservative chloride of copper, mechanically fixed in posi- 
tion by the insoluble salt, sulphate of baryta. 

The second is the " Thilmany, new process."* Here the first impreg- 
nation is sulphate of zinc, the second chloride of barium, and the resulting 
salts, chloride of zinc fixed as before by sulphate of baryta. 

The third is known as the tan-zinc process. The first impregnation is 
with chloride of zinc dissolved in a solution containing 2^ per cent, of 
glue. This is followed by an injection of a tannin solution which precipi- 
tates the glue, forming tannate of gelatine, a perfectly insoluble com- 

* For specifications of this process, see Appendix No. 6, 



CONSTRUCTION AND MAINTENANCE OF ROADS. 139 

pound, and which fixes the chloride of zinc so thoroughly that it cannot be 
extracted either by boiling or steaming. I am not now prepared to state 
which of the three processes is the best, as our experiments are still going 
on. It may be safely asserted, however, that no system of treatment de- 
pending on a soluble salt, as in the Burnett or Boucherie processes, is of 
any value unless the salt is fixed in the wood by a subsequent injection 
which will fill the pores with an insoluble substance. I have procured 
specimens from various Burnettized bridges, and the analysis has shown 
in every case that the zinc had been entirely washed out of the wood. 
In treating wood by either the cresote or metallic salt systems the anti- 
septic injection is virtually worthless unless the wood has been previously 
<leprived of its sap. In doing this the following rules should be rigidly 
observed : 

First. — The steam bath should not exceed 5 pounds pressure, or 240 
<ieg. F. in temperature, and the lumber should remain in the bath for not 
less than 90 minutes for sticks under ten feet in length, and 9 minutes 
additional for every additional foot of length. 

Next. — The steam bath should be followed by an exposure to a 
vacuum of not less than 1 1 pounds pressure for 40 minutes for sticks less 
than 10 feet in length and 6 minutes more for each additional foot, after 
the vacuum is reached. 

Last. — The preservative injection should be run in while the vacuum 
is still on, and after the cylinder is filled the injection pressure should be 
brought up gradually to not less than loo pounds. The time for its con- 
tinuance will vary with the wood used and the length of the stick. 

By the observance of these rules in treatment and the selection of 
thoroughly sound lumber, it is in my opinion perfectly practicable to pro- 
duce a good wooden paving block, which, when properly laid, will make 
a clean and lasting pavement. Treated gum blocks placed in the testing 
machine at the St. Louis Water-Works stood the passage of 95,000 
wheels with a wear of only one-eighth of an inch. The wheels of test- 
ing machine were loaded to 2,000 pounds per wheel, or 800 pounds per 
inch of tire width. 

It is hardly necessary to reiterate, however, that no system of treat- 
ment, however good, will arrest decay, convert unsound blocks mto sound 
ones, or render blocks cut from dead trees fit material for a pavement. 

E. R. Andrews. — I do not wish to advocate the use of de- 
cayed timber, or to intimate that by the process of creosoting, wood which 
has lost its quality by reason of decay can be restored to its original 
strength ; but if partially decayed timber be creosoted the process of 
decay is arrested, and there may be cases where it will be advisable to 
creosote it, and thus save for future usefulness timber which would other- 
wise be valueless. 



I40 CONSTRUCTION AND MAINTENANCE OF ROADS. 

As an instance of such an experiment, I quote from \ht Journal of the 
Society of Arts, London, June ist, i860, containing a paper by G. R. 
Burnell, entitled " On Building Woods, the Causes of their Decay, and 
the Means of Preventing it," and a discussion thereon by the members of 
the society, during which Mr. John Bethell made the following statement 
(see page 565). 

" That in timber where decay had commenced it had been stopped by 
the injection of creosote. He could confirm that fact by stating that 
about twelve years many thousand sleepers were packed upon the Lanca- 
shire & Yorkshire Railway some time before being used. When they were 
about to be used they were found to be more or less decayed, and it was 
a question whether the whole should not be sold for firewood, when it 
was determined to submit the sleepers to the process of creosoting. After 
those sleepers had been down for ten years it was found that not only had 
the decay been arrested, but the sleepers were as good as if they had beea 
sound, new timber." 

I do not quite approve of General Smith's specificatioi.s for the treat- 
ment of timber. Unless he has positive proof to the contrary, I should 
doubt whether large-sized timber can be properly dessicated in ninety 
minutes. In my own experience I find that the time required is greater 
with large timber than with small, and in proportion to its square rather 
than its length. Wood is a slow conductor of heat, and a 12-inch by 12- 
inch stick cannot be heated through to a point of vaporization in ninety 
minutes, and the moisture cannot be withdrawn until it is vaporized. 
Moreover, it will require a vacuum of 20 to 25 inches duHng several hours 
to withdraw the vapor, so that danger of decay from moisture within the 
wood shall be removed. If this is not accomplished before injection with 
creosote, the effect will be to close up within the wood fermentable sub- 
stances. Thorough injection cannot be effected. The incompressible 
water will not permit the oil to permeate those portions of the wood 
where it exists. 

Engineers should give time enough to do good work. In the practice 
abroad and in this country, where creosoting is done intelligently, the 
work is never hurried. Large piles and square timber cannot be properly 
dessicated and creosoted in less than from 20 to 24 hours. Such work 
costs more money, but is cheapest in the end. Paving blocks can be 
treated much more rapidly. During the infancy of creosoting in this 
country great care should be taken to secure thorough work in order to 
obtain for such timber the longevity attained in Europe and the confi- 
dence of consumers. 

David E. McComb. — I shall confine my remarks to granite and 
bituminous pavements as laid in the cities of Washington and George- 
town, D. C. 

The standard stone pavement has a base of six inches of hydrauUc con- 



CONSTRUCTION AND MAINTENANCE OF ROADS. 141 

Crete, upon which is spread three inches of sand, in which the granite 
bloclis, measuring eight inches by four inches by six inches in depth, aver- 
age, are bedded with close joints, which joints are filled with screened 
gravel, pea size, heated to a temperature of 400 deg. F. The blocks are 
then brought to a solid bearing by the use of the ordinary rammers, after 
which the joints are filled with coal tar refined to 400 deg.. F., which 
removes the light oils, water, etc., yet retains the heavy oils, " cut back," 
which is the result ot a mixiure of the residuum of the destructive distil- 
lation of coal tar, wnth still bottoms, being carefully guarded against. 
After the joints have been filled with the tar, as before described, fine 
heated sand, or perfectly pulverized limestone, is spread over the surface, 
which completes the pavement. In situations where the sub-foundation 
is solid and unyielding, the concrete base is dispensed with, six inches of 
,gravel, compressed by a heavy steam roller, being substituted in its stead. 

All the different kinds of tar pavements have been laid and tested in 
Washington, and our experience is that they are not economical, requiring 
too extensive repairs and too frequent renewals. 

The only two pavements that have given any reasonable degree of 
satisfaction are those having a mixture of Trinidad bitumen and coal tar, 
refined to 400 deg. F., in approximately equal proportions as the cement- 
ing medium of the sand, limestone, or other ingredients forming the body 
of the wearing surface. Such a top coating is good for about seven years, 
requiring, however, watching and small repairs during this time, after 
which it seems impossible to patch it successfully. 

There have been laid six squares of Neuchatel under two different con- 
tracts, the first in 1872, the latter in 1876. That laid in 1872 on I street 
has stood the test of time and limited travel very well, and is in fair con- 
dition now. That laid in 1876, on Pennsylvania avenue, is in very poor 
condition, and requires extensive repairs. This class of pavement possesses 
one fatal objection, viz., its extreme hardness, as a consequence of which, 
when the surface is covered with a film of water, it is only by the exercise 
of great care that horses can travel upon it without slipping and falling 
oftentimes, especially in turning corners. 

The pavement of this general class that has given the most satisfaction 
has for its foundation a depth of six to eight inches of hydraulic concrete, 
upon which is spread a coat of asphalt mastic half inch thick, which is 
intended to give an uniform surface to compress the top coat upon. This 
cushion coat, as it is termed, is composed of 62 parts of fine sand, 15^^ 
parts of pulverized carbonate of lime, and 22^ parts of asphaltic cement ; 
all the compression given to this coat is that due to rolling with a hand 
roller weighing about ten pounds per inch run. The top coat, or wearing 
surface, is composed of 65 parts of fine sand, 16 parts of pulverized lime- 
stone and 19 parts of asphaltic cement. The sand is required to contain 



142 CONSTRUCTION AND MAINTENANCE OF ROADS. 

not more than five per cent, of clay, and to be a little finer than would be 
usually accepted for use in making mortar ; the asphaltic cement is com- 
posed of refined Trinidad asphalte and refined petroleum still bottoms, or 
paraffine oil in the proportion of loo pounds of the former to 19 pounds of 
the latter. The pulverized carbonate of lime is mixed, when cold, with 
sand heated to 300 deg. F., which mixture is then mixed with the asphaltic 
cement, heated also to 300 deg. F., and a thorough incorporation is effected 
in a twin pug mill, after which the material is carried in carts, having an 
arrangement to keep it hot, to the work, and is spread upon the cushion 
coat with rakes, and having a thickness of 2 8-10 inches. It is then rolled 
with the hand rollers before referred to, the jointings at the cUrb being 
tamped with the pi!on described by Mr. North, which is heated to a tem- 
perature of 500-250 F., the test of its being too hot is that it scorches a 
white pine plank, on hand for the purpose of trial. The surface is then 
rolled with a steam roller weighing 300 lbs. per inch run, of large disk. 
No difference is observable between rolling with cold or heated roller^ 
The disks of the roller are kept moistened with crude petroleum, which 
prevents any tendency to pick up the top coat, and when the proper pro- 
portions are observed no trouble is experienced from the machine shoving 
the material ahead, this occurring when the mixture is too rich in asphaltic 
cement. After being compressed, the thickness of wearing surface is two 
inches. 

The gutters are paintwithed asphaltic cement ironed in, the object 
being to prevent the degradation that occurs at this portion of the carriage- 
way, caused mainly by the fact that this portion of the carriageway does 
not share with the traffic compression produced at the other parts of the 
roadway. 

Trouble has been experienced on pavements alongside of street rail- 
road tracks, the cross ties of which, if not well ballasted, move up and 
down sufficiently to break the pavement over them and leave ugly ridges. 
The tendency to cut into ruts alongside of the rail is counteracted by laying 
granite blocks, eight inches by four inches by six inches, alternately as 
header and stretcher, bedded in mastic, the toothing thus formed obviating 
this tendency to rut. 

The above described pavement, when honestly proportioned and laid,. 
possesses all the elements which go toward m^aking a good pavement, and 
It is not expensive, costing at the present time about $1.75 per square yard. 

I agree with Mr. North that a bond for maintenance for a term of years 
should be required from the contractor for this class of work, there being 
so much of honesty and skill required in refining and manipulating the 
materials composing it. 

E. P. North. — I would like to ask Mr. McComb how much clay is left 
in Trinidad bitumen and how it is refined. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 143 



D. E. McCoMB. — There is supposed to be left in the refined bitumen 
twelve per cent, of impurities, it being practically impossible to refine it so 
that it will have a smaller percentage of impurities than that. 



Note on the Nomenclature of Bitumens, 
by edward p. north. 

While such strenuous efforts are being made for uniformity in the 
matter of measures, the nomenclature of bitumens should secure attention. 

In Paris, and in France generally, the nomenclature of M. Malo and 
others, as given in Transactions, Vol. VIII., page 121 (May, 1879), is used. 
Colonel Haywood also employs it in the specifications and reports of the 
City of London, and it is believed that all dealers and manufacturers of 
asphaltes use the same nomenclature. 

On the other hand, in this country dealers in Trinidad bitumen and its 
mixture almost invariably call their compounds asphalt or asphaltum. 
Tar pavers and roofers also apply the same names to their products, both 
calling such asphaltes as are capable of compression Neuchatel, apparently 
because the Val de Travers asphalte happened to have been imported into 
this country by a branch of the " Neuchatel Asphalte Company, Limited," 
of London, which bought out "La Societe Generale de Asphaltes de 
Suisse," but could not take the name Val de Tra\ ers, as there was at that 
time an organized company in London bearing that name, Val de Travers 
asphalte is not called Neuchatel in any part of Europe, besides which there 
are at least three other asphaltes that can be compressed, besides many 
others that are used for mastics. 

As the distinction between asphalt or asphaltum on the one hand, and 
asphalte on the other is too slight to attract attention of any but a critical 
reader, the advisability of following Malo's nomenclature is submitted to 
the Society as the most logical and convenient. 

F. RiNECKER, of Wurzburg, Germany (through the Secretary).— Be- 
sides the methods of paving described in the paper of Mr. North, the fol- 
lowing may be worthy of a short mention : 

Brick pavement, especially in Holland, where very hard brick, Klinker, is 
used for this purpose. 

Flag pavement, in many Italian towns, consisting of large slabs, laid in 
rows for the wheels to run over, the balance of the street being com- 
mon pavement. 

Concrete pavement, which (if I am correct) was tried in Paris and New 
York. I am ignorant of the results, however. I have seen some 
sidewalks and depot platforms in Germany, which wear well. For 
traffic it will be worthy of consideration, whether the broken stone or 
gravel used in the concrete should not be of the same hardness as 
the cement to insure equal wear. In using harder stone the unequal 
wear might be a cause of failure. 



144 CONSTRUCTION AND MAINTENANCE OF ROADS. 

In selecting any system for covering roads and streets uniformity is 
necessary throughout a whole city, at least in its main thoroughfares. 
The safety of horses greatly depends on their shoes, but the patterns of 
the shoes differ with the roads on which they are to be used. The con- 
nection between shoes and roads needs no comment, and in my opinion it 
is a grave mistake to use stone in one street and wood in another, when 
the same traffic has to run over them both. 

I attach some notes taken from German and French periodicals, the 
figures of which I have reduced to United States standards. 

As to the cost of some pavements to the square yard, the Deutsche 
Bauzeitung, 1S77, has the following : 

Vienna. ,■ — London. v, 

Granite. Granite. Asphalte. Wood. 

Durability, years 35 15.6 17 11.34 

Cost of construction $3.07 to $3.37 p. 77 $3.80 $3.20 

Total cost of maintenance 1.74 1.40 3.27 3.37 

Aggregate cost averaging to one year. 13 .37 .34 .62 

From experience at Buda Pesth the following data for 1 5 years are 
furnished : 

..—Granite on— >^ Trachyte on Asphalte corn- 
Broken Broken prime* on 
Stone. Concrete. Stone. Wood. Concrete. 

Thickness of pavement, inches 7.1 7.1 7.1 ? 2.36to2.76 

" "■ foundation 6.3 6.3 6.3 ? 9.7 

Cost of construction $4.50 $5.05 $5.50 $3.00 $4.35 

Total cost of mainteaance 2.40 1.80 3.00 6.00 3,00 

Aggregate cost of 15 years, averaging to 

one year, cents 46 .45 .57 .60 .49 

The paving stones of Paris are described in " Romberg's Zeitschrift f. 
pract. Baukunst," 1878, as follows : 

According to the specifications a distinction is made between large and 
small blocks. 

Large blocks to be 7.9 to 9.2 inches long, 6.3 to 9.2 inches wide and 7.9 
to 9.2 inches high. 

Small blocks to be 6.3 inches long, 3.9 inches wide and 6.3 inches high. 
The latter, ''paves de petit echantillon" are preferred of late. Differences 
in size to 0.4 inch are admitted. 

On account of the bond, a certain percentage to be blocks one and 
one-half times as long as specified above, "boutzsses." 

According to the dressing, two qualities are distinguished : smooth and 
rectangular blocks for joints of only 0.2 inch, and rough ones for joints up 
to 0.6 inch. 

The material is sandstone, "gres d'yvette des Vosges" or "de I'Ourtke," 
and porphyry from Belgium and Bavaria. This porphyry, however, has 
not given satisfaction, wearing too smoothly. 

The price is $44 to $125 the thousand, and $8 to $13 additional for 
dressing. 

The Macadam is being replaced where annual repairs exceed 50 cents 
the square yard. 

* Asphalte comprime la the French term for the codq pressed powder. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 145 

As to the cost of the Paris pavements, the following notes are from 
"Annales des ponts et chaussees," 1877 and 1878 : 

Pavement. Macadam. Asphalte. 

Cost of construction S2. 55 to $3.45 ? $1.93 to $2.42 

Annual cost of maintenance, cents 9.6 29.0 17,7 

The wear of Macadam, amounting to 23.37 cubic yards to the mile 
and 100 horses. 

Annual cost of maintenance to the square yard : 

1872-5. 1876. 1878- 

Pavements, cents 7.7 8.2 8.5 

Asphalte, '■ 19.8 20.9 20.4 

Macadam, " 29.0 34.0 32.2 

The watering with carts costs : 

On Macadam 19.3 cents to 1,000 square yards. 

On pavements 9,6 " " " 

J. B. Dumas, Assistant Engineer of the City of Paris, published com- 
parative estimates in " Nouv. Ann. de la Constr.," 1878-79, from which 
the following data are compiled : 

Price to 
Cost of construction. the yard. 

Pavement of rectangular blocks "firres," ^.9 by 6.3 by 6.3 inches $3.22 

Macadam of silex . 1.61 

" " meuliere 1.84 

" " porphyre 1.98 

Asphalte comprlme, 2 inches thick on 3.9 inches concrete. 

Using for the latter hydraulic lime 2 . 98 

" " Koman cement 3.08 

" Portland 3.15 

Each inch of asphalte above 2 inches additional 1.05 

Wood pavement, Trenaunay 2.76 

Norris 4.31 

Annual cost of maintenance and repairs: 

Eapaving 24 to 64 cents. 

Asphalte, roadway 21 " 

'• crossings 32 " 

" sidewalk 4.8" 

Macadam, silex 47 '' 

'• meuliere , 55 " 

" porphyre 129 " 

Wood pavement .56 " 

Both systems of wood pavements failed in streets with high traffic. 
Experiments with asphalte coule* have shown its unfitness for wagon traffic. 

The Engineer, 1878, Vol. XLVI., p. 358, ascribes the invention of the 
Macadam to John Lochhead in 1794. 

J. J. R. Croes. — Referring to the amount of water used for keeping 
down the dust on Macadamized roads (p. 82), the following may be of 
interest. 

In the year 1872 an account was kept of the water used on the drives 
in the Central Park in New York City. 

The length of carriage ways is 9.435 miles, of widths "froa: 30 to 60 
feet, averaging 54 feet. The area occupied, including spaces for car- 
riages in waiting, is very nearly 250,000 square yards. The carts used fcr 
watering are in the form of a segment of a cylinder of 35 inches diameter, 

* Asphalte coulu (poured) is the French term for mastic. 



146 CONSTRUCTION AND MAINTENANCE OF ROADS. 

the height being 26;^ inches and the chord 20 inches. The barrel is 90^ 
inches long, and contains 40.7 cubic feet of water. 

During the season of 1872, from April ist to October 31st, the roads 
were sprinkled on 136 days, using 81,30$ barrels of water, or 3,309,114 
cubic feet, an average of 24,332 cubic feet per day, or 97 >^ cubic feet per 
day for each 1,000 square yards. The greatest amount used in any one 
day was on July ist, when the temperature ranged from 'j'j degrees to 93 
degrees F., and 929 barrels or 37,810 cubic feet of water were used ; an 
average of 151 X cubic feet per 1,000 square yards. 

The next greatest amount used was on June 22d, when the temperature 
ranged from 70 degrees to 86 degrees F., and 890 barrels or 36,223 cubic 
feet of water were distributed ; an average of about 145 cubic feet per 
1,000 square yards. 

At least one-half of the area watered was sprinkled twice as often as 
the other half, in consequence of its greater exposure and the greater 
travel upon it. 

I am informed that during the summer of 1879 the carriage way of 
Tifth avenue from Twenty-third to Thirty-fourth streets, 0.55 mile in 
length and 40 feet wide, embracing 12,907 square yards, was kept watered 
by six carts holding 70 cubic feet each, and making from three to six trips 
per day. This would make the amount of water used from 97.5 to 195 
cubic feet per 1,000 square yards. The pavement is of trap blocks. 

E. B. Van Winkle. — Referring to Mr. North's paper : The form of 
roller proposed for the upper layers of earth roads, namely, large and 
smaller sized disks placed alternately on the axis of the roller, I have £ een 
used with excellent effect on an embankment, and it could doubtless be so 
used for the foundation of earth roads, but is unsuitable for surfacing and 
xoad maintenance. The ridges left by the use of this form of roller would 
tend to carry surface water longitudinally instead of the shortest distance 
transversely to the gutters. 

I believe it would be found very efficacious and economical in the main- 
tenance of earth roads to have the regular passage over them — one or 
XQore times, according to their importance — of a moderately heavy two- 
liorse roller a few hours after the cessation of rains. About one roller to 
■eFery twenty miles of ordinary road should be kept provided. 

Referring to page 65 : I should think it questionable whether the addi- 
tion of hard pan to a clay road would be of use. 

Referring to pages 68 and 69 : It would be interesting to know the 
results of a combination of the first and last of the systems of rolling 
Macadam roads enumerated by Mr. North, that is, steam rolled and traffic 
made. I would suggest that the steam roller be first used without bind- 
ing material, or with very little, to bring the road metal to a passable sur- 
face, and then open the road to traffic. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 147- 

My experience coincides with that of Mr. North — that the hardest kind 
of stone, if of the proper size, will produce a firmer roadbed when traffic 
made, without softer binding material. 

Referring to page 71 : The reason why the Macadam in Basnat street, 
Liverpool, does not show the wearing qualities of a well-puddled trap 
road I conceive to be not on account of the binding material — coal tar, 
pitch, &c. — but owing to imperfect consolidation due to hand rolling. 
I have no doubt that, the rolling being equal in all cases, a binding 
material of pitch as described would give better results than where cement^, 
clay, or " hoggin " were used, as less water would reach the foundation, . 
and the pitch would have more elasticity, giving somewhat without break- 
ing or crushing. 

Referring to page 72 : M. Malo's picturesque description of the Macada- 
mized streets of Paris will apply with equal force to London or New York. 

As far as I have any experience. Macadam pavements are a failure for 
city streets, except in some isolated cases where the traffic is merely nom- 
inal, or where all other considerations except pleasure driving are out of 
the question. 

Referring to page 7^ : One great reason for the unexpected success 
of Mott avenue was, in all probability, that the heavy rolling over the sat- 
urated fresh filling of earth of the road (some four or five feet in depth) 
most thoroughly compacted it, hence giving subsequently a very solid 
foundation for the Macadam. 

Referring to pages 81 and 82: The transverse section of a pavement 
is most important. The general tendency is to give too much crown to- 
the pavement. In streets where there are horse railroads this crownings 
has generally become excessive, the trackmen tending always to raise the. 
track regardless of any established street grade, while the city employes 
who repair the pavements meekly assume that the track is at grade and 
pave flush with it, while at the same time the curb is maintained at grade 
or settles below it. It would seem proper that the authorities in charge 
of street roadways should, at the time a railroad is being built, determine 
a proper profile for it. This profile should be filed, and the railroad forced 
to conform to it. 

Another fallacy is, that an excessive amount of crowning adds to the 
strength of the pavement on the principle of an arch, the paving blocks, 
being the voussoirs and the curbstones the skewbacks. The absurdity 
of this illusion is readily apparent if we conceive of an arch of 30 to 60 
feet span with a versed sine of one foot or less, skewbacks half a foot 
thick resting on compressible earth, and, more wonderful still, the 
voussoirs in contact only at the extrados. The greater the crown given 
to a pavement the less will the depressions resulting from poor paving be 
noticeable on account of holding water. 



148 CONSTRUCTION AND MAINTENANCE OF ROADS. 

In an earth road the transverse slope should never be less than the longi- 
tudinal slope. The restriction I consider unimportant in a stone block 
pavement, as with this class of pavements there is no danger of ruts being 
formed by running water, while it is quite desirable to have the rainfall 
scour quite an extent of the pavement surface before reaching the 
gutters. 

Gillespie says that the proper section of roadway surface should be 
formed by two planes inclined from the gutters upward towards the centre 
of the roadway, with their intersection rounded by a slight curve. 

That this is correct I have tried to believe for a long time, but obser- 
vation convinces me that it is not the best form. The arc of a circle is 
practically the best cross section for street pavements. If not from choice, 
at least from necessity, the bulk of travel is along the centre of the street, 
the portions on each side next the curb being occupied by vehicles stand- 
ing. With a section of the arc of a circle the centre of the roadway is al- 
most level. Another advantage is, that while the gutters are running 
full, the width of deep water is narrower than when the surface is an in- 
clined plane. 

Referring to page 83 : I fully agree with Mr. North as to the excel- 
lence of granite pavements in England. London, particularly, excels in 
the quality of its stone block pavements. I have seen nothing elsewhere 
equal to them for streets of heavy traffic. Their great superiority arises 
principally from their concrete foundations. It is surprising that similar 
foundations are not always used when the streets in the business portion 
of the city are relaid with stone blocks. The filling of the joints between 
the blocks with pitch I think would be a decided improvement upon the 
London plan of grouting. 

Referring to page 84 : Wood pavements, as far as I have any experi- 
ence, have been without exception a failure. I can conceive that creosot- 
ing the blocks and filling the joints with bitumen would prevent decay, 
and thereby materially lengthen the life of this class of pavements, but, so 
far, nothing has been — and in all probability never will be— invented that 
will prevent wood, when subjected to an incessant impact and attrition of 
iron horseshoes and heavily loaded steel tires from acting as wood — that 
is, quickly wearing down. The pits in the surface of wooden pavements 
have been proved by borings to be due much more to the actual wearing 
off of the wood than to settlement. 

Referring to page 97 : My recollection of those sidewalks in Paris 
covered with asphaltic mastic (" bitumen" so called) is, that they are not 
very satisfactory. During July and August almost every footstep left an 
impression in the mastic, and in winter they were excessively muddy, and 
had generally sunk out of plane. 

Have any experiments ever been made with the bituminous limestones 



CONSTRUCTION AND MAINTENANCE OF ROADS. 149 



found in this country, to use them as paving material in tbe same manner 
as the regular asphalte ? ^ 

John Bogart. — Experiments were made some years ago in Chicago 
with a peculiar limestone, which it was thought might be utilized in a 
manner similar to the imported asphalte. The result was a good Mac- 
adam pavement, but apparently the impregnating matter had no advan- 
tageous effect — my recollection is that it was petroleum rather than 
bitumen, and that it did not exert any cohesive force. 

C. C. Martin. — The Smith Hydraulic Stone Crusher as now manu- 
factured possesses two peculiarities which render it superior in certain 
respects to former patents : 

First. — The power is applied through an hydraulic cylinder, which 
has connected with it a safety-valve. 

Second. — The opening through which the stones pass after being 
crushed is wider at the bottom than at the top, as shown by the cross- 
section at c c. 

These are the two essentially novel and good features of the machine ; 
all of the rest are simply mechanical arrangements for transmitting the 
power from the engine to the machine, and may be arranged as here shown 
or in any other way. In this machine a is the hydraulic cylinder, b is the 
frame, c is the movable jaw, ^the toggle, e the hydraulic ram, /the plunger, 
g the connecting rod, h the band -wheel, k the fly-wheel, /the stationary 
jaw ; the section ^ <f is a front elevation of the stationary jaw. When the 
machine is to be made ready for use the ram, e, is drawn back so as to 
place the movable jaw, c, far enough from the fix.ed jaw, /, to permit stones 
of the largest required size to pass through betvyeen them ; the plunger,/, 
is drawn up out of the hydraulic cylinder, a, and the cylinder is then filled 
with water or other liquid, and the safety-valve is weighted. The opera- 
tion of the machine is as follows : Stones are thrown between the jaws 
and the engine started ; as the crank shaft revolves the plunger,/, is forced 
down into the liquid, and, displacing a portion of it, forces the ram for- 
ward, which, through the toggle, d, presses the movable jaw against the 
stone, which is crushed. The upward movement of the crank withdraws 
the plunger, and the ram is drawn back to its original position, and the 
jaw is again opened : thus, every revolution of the crank shaft produces 
one stroke of the jaw. The machine works well, running at two hundred 
to two hundred and fifty revolutions per minute, and will readily and 
regularly break seventy-five cubic yards of limestone in ten hours to sizes 
varying from lyi to lyi inches largest dimensions. 

The advantage of the safety-valve is, that in case any stone which can- 
not be broken, a sledge-hammer dropped from the hands of a careless 
workman, or any other unyielding body, gets between the jaws, the only 
effect is to force open the safety-valve and permit the escape of a portion 



ISO CONSTRUCTION AND MAINTENANCE OF ROADS. 




HYDRAULIC STONE CUTTER (SMITH'S PATENT), 
discharged is received in a small tank, and the continued motion of the 
machine pumps it back into the cylinder, and the crushing goes on. If 
of thte liquid from the cylinder, thus stopping the motion of the jaw with- 



CONSTRUCTION AND MAINTENANCE OF ROADS. 151 

out stopping or changing the motion of the fly-wheel, The liquid thus 
the obstruction still continues, the safety-valve is again opened. The result 
of this safety attachment is that the machine is never broken. 

The advantages of widening the jaw at the bottom are twofold, as 
will appear from a consideration of the operation of the stone in the 
crusher. The broken stones occupy more space than the unbroken, and 
the smaller the pieces the more space do they occupy. The stone enter- 
ing at the top of the jaw is broken, and each successive stroke crushes it 
more, and in the old style of jaw the stone became clogged and many 
pieces were ground to powder before they could escape, thus wearing out 
the jaws and cheek pieces, and consuming unnecessarily a large amount 
of power. The widened jaws permit the stones to escape as soon as they 
are broken, thus leaving them of more uniform size, making less dust, 
and breaking them with the least possible expenditure of power. 

Edward P. North. — Regarding objections made to certain clauses 
in the paper under discussion, it may be said that the roller with unequal 
sized disks was not advised for maintenance, but unless it was so guided 
that the larger disks always followed the same tracks its use would cause 
less tendency to longitudinal ruts in the road than the ordinary traffic. 

The advisability of surfacing a clay road with hard pan must depend 
greatly on the character of the hard pan — a clay hard pan might be ob- 
jectionable. 

Messrs. Spielman & Brush's practice, as detailed on p. 119, is un- 
doubtedly sound under the circumstances, viz. : an absence of water for 
compacting and puddhng, but a better road, with less tendency to inter- 
nal wear, would have been formed by a steam roller, if sufficient water 
could have been procured. 

Lavoinne seems to have misunderstood the effect of the screenings, 
/. e., small fragments of stone from the breakers. The coarser of these 
are appHed only when compacting has proceeded so far that the stones have 
a tendency to roll over one another and round their angles ; these screen- 
ings bind the stone and prevent to a great extent further wear. About 
33 per cent, of screenings are worked into the metal and are used in pud- 
dling. Probably about 25 per cent, of this is coarse screenings in the 
interstices between the stones, the rest being fine screenings and that 
used in puddling. 

Law & Clarke, p. 145, give 10 or 11 cubic feet interspace per yard — 40 
per cent, in compacted stone. In Paris, about 24 per cent, of sand is used 
in binding, and, as above stated, 33 per cent, of screenings are used here. 

It was not the intention to argue for poorly constructed wooden pave- 
ments, but rather to show the practice where wood pavements are suc- 
cessful, with the hope that it might be followed in this country. The fact 
that wood pavements as usually constructed here, and never repaired, have 



152 CONSTRUCTION AND MAINTENANCE OF ROADS. 

proved failures, cannot be denied, but that a well made and intelligently 
maintained wood pavement would be a failure is doubted. 

The following memorandum from Cleveland confirms this view : " In 
the year 1873 5,070 square yards of creosoted wooden pavement were laid 
in Franklin street, Cleveland. The pine blocks were creosoted with about 
4 pounds of oil per cubic foot. Since that time no money has been 
expended in maintenance, and the pavement is in excellent order. 

"At the same time, and in the same street, an equal area was laid with 
blocks prepared by the * Thilmany' process; of this, 1,400 square yards 
have been relaid by the city." 

It is unfortunate that the asphalte pavements in Washington were so 
poorly laid. 

I street has such an excessive crown that it is only in the centre of the 
wheelway that the street is sufficiently flat for ease or comfort in driving. 

On Pennsylvania avenue the transverse profile is good, but the heated 
powder was apparently laid on damp concrete, and the surface is badly 
cracked in consequence, and has been extensively repaired, though it was 
laid in the fall of 1877, and it is doubtful if it wears more than five years 
in all. 

In Paris, with a much heavier traffic, asphalte lasts 1 5 years. 

The bituminous mastic pavements described by Mr. McComb present 
very fine surfaces, and, if they wear as well as now hoped, will have all 
the advantages of compressed asphalte, except durability, at reduced cost, 
and their use may be advisable in streets of light traffic. 

The present practice is to make the wearing surfaces harder than has 
been usual, it having been held that all mastic pavements, subjected to 
street traffic, should be made so soft as to dent in summer, to prevent 
their breaking up in winter. 

The weak paint of bituminous mastics seems to lie in the expense 
necessary to free the Trinidad bitumen from clay, and the difficulty of 
getting sand that is free from clay, and fine enough to absorb sufficient 
bitumen for cohesion in cold weather, without an excess in hot weather. 
Loam or loamy sand was used at first to enable the mixture to carry 
sufficient bitumen for wear, but the rapid rotting in the gutters, and at 
other points whefe water lies, has led to the use of 15 to 16 per cent, of 
limestone, ground to pass through a sieve with 26 meshes to the inch, 
which probably will not be so detrimental to the mastic as clay. 

In reply to a question as to the amount of clay allowed in mastic 
work in Europe, M. Leon Malo writes : " In principle, no clay at all 
ought to be in mastic ; the asphalte rock, being quite pure limestone, is 
desired to be mixed with quite pure bitumen. But, in reality, the bitu- 
men of Trinidad having been generally adopted in works by want of pure 
mineral bitumen, and as it is impossible to quite deprive that bitumen of 



CONSTRUCTION AND MAINTENANCE OF ROADS. 153 

its clay, it is admitted that the clay brought into the asphalte works by the 
Trinidad bitumen can be accepted ; that is to say, from 2 to 3 per cent, of 
clay in the mastic. For the compressed asphalte, to which no bitumen is 
added, not one quantity of clay is allowed." 

Regarding the asphaltic mastic sidewalks of Paris, it should be noted 
that there is always a temptation on the part of the mastic workers to use 
too much bitumen, as the larger the percentage the more easily the mastic 
is worked ; and, unless it is kept very low, the pavement will dent in hot 
weather. The mud must have been brought on from the wheelways, as, 
according to Chabrier, the mastic sidewalks under the arcades of the Rue 
de Rivoli, Paris, wore about half an inch in 13 years — too small a wear to 
produce much mud. 

The necessity for better pavements than those offered by the 
prevalent granite blocks, will justify the insertion of a translation from 
M. Leon Malo's " Note sur L'Eiat Actuel de L! Industrie de V Asphalte 
Paris, 1879." 

The experiment of compressed asphalte for carriageways has now been 
made. It has shown its defects and its advantages ; we do not hesitate to 
say that its advantages far exceed its defects. 

We do not now speak of its noiselessness nor of its precious property 
of creating neither dust nor mud ; of its agreeable aspect to the eye, which 
is a quality not to be neglected in the ensemble of the embellishment of a 
city ; we have shown the importance of these in our first work. We insist 
only on its action upon the public health ; a point which we did not 
sufficiently emphasize. 

The asphalte, pfaced over the soil, like a layer of caoutchouc, abso- 
lutely intercepts any communication between the soil and the atmosphere ; 
it does not allow rain water, which runs rapidly into the sewers, to pene- 
trate ; and thanks to its water-repelling (" hydrofuge ") character, the 
carriageways dry as soon as the rain has ceased. 

A stone pavement, on the contrary, permits a constant communica- 
tion between the soil and air through its joints. All the impurities of the 
surface, dissolved by the surface waters, are by them carried into the 
earth ; then, when the sun strikes it, these impure waters are evaporated, 
returning miasma, bred below the pavement, into the air ; it is an evil 
which has been long recognized and uncontested, but against which no 
remedy is known. 

The system of joining pavements with asphaltic mastic might, per- 
haps, obviate it, but it is very costly, and renders the carriageway ex- 
tremely hard for vehicles. Compressed asphalte seems to have solved the 
problem ; and we are compelled to think that of all the services which it 
can render, this is the most efficacious and the most precious. To be 
sure, the influence of deleterious miasmas radiated from the different sys- 



154 CONSTRUCTION AND MAINTENANCE OF ROADS. 

terns of pavements with open joints, cannot be analyzed in a precise 
manner ; it is judged rather by induction than by a direct observation 
which can be put in figures ; but it is not the less evident and not the less 
to be dreaded. 

M. Malo also gives the following tabulated results of analysis made in 
the laboratory de L'Ecole des Fonts et Chaussees on different asphaltes: 





Valde 
Travers, 


Seyssel. 


Lobsan. 


Sicilian. 


Maestu. 


Forens. 


Water and matter volatile at 
212° F^ 


0.50 

10 10 

87.95 

" 

0.25 

0.30 

0.45 
0.45 


1.90 

8.00 

89 55 

(( 

0.15 

0.10 

0.10 
0.20 


8.40 
11.902 
69.00 

3.05 

5.70=» 
5.00 
0.30 

1.65 


0.80 

8.85 

87.50 

0.60 

0.90 

0.95 

0.40 


0.40 

8.80 

9.15 

57.40 

4.35 

8.10 

11.35 
0.45 


^5 




2 25 


Cabonate of lime 


97 00 


Siliclous sand 

Aluminum and peroxide of 


0.15 


Sulphur 

Carbonate of magnesia 

Different minerals insoluble in 

acids 

Loss 


0.20 

0.05 
0.10 








100.00 


100.00 


100.00 


100.00 


100.00 


100.00 



Notes. 

1 . The water given above depends on the dryness of the sample at the 
time of analysis ; the figures not being of importance in the result. 

2. This quantity appeared to contain a certain proportion of oil, which 
was mixed with the bitumen and was not exactly determined. 

3. This comprises 4.45 of iron, combined with sulf)hur. 

M. Durand-Claye, Director of the laboratory, speaking of the Lobsan, 
says : " It contains about 9>^ per cent, of pyrites, which may become the 
cause of failure in employing this material. The heat to which it is sub- 
mitted may cause it to lose half of its sulphur, and be transformed into 
protosulphate of iron, an oxydizable material, which by exposure to the air 
is transformed into a soluble sulphate of iron ; disintegration may result 
from this a short time after putting it in place." 

Mr. H. F. Starr, of the Columbia College School of Mines, kindly 
made an analysis of some Limmer asphalte, which gave the following 
result: 

Bitumen 8.26 

Clay 4.98 

Carbonate of lime 56. .54 

Carbonate of magnesia 27.01 

Sesqui-oxide of iron 3.21 

100.00 

This is the only analysis I have seen of an asphalte that will not com- 
press, and the only one, excepting the Maestu, in which there is over one 
per cent, of carbonate of magnesia. 



CONSTRUCTION AND MAINTENANCE OF ROADS. 155 



M. Malo gives analyses of seven different cargoes of crude Trinidad 
bitumen. In each case the samples were thoroughly dried, losing from 32 
to 38 per cent., after which the average of the analysis was bitumen S^%> 
and clay 48^ per cent. The greatest percentage of bitumen in any sample 
was 57.55, and the least 45. 

In addition to the description of the hydraulic crusher furnished by Mr. 
Martin, a mention of the new Blake crusher may be of interest. See figure. 




In it the old cast-iron frame is replaced by steel rods and a wooden 
frame, so cushioned that the fly-wheel, in case of abnormal resistance, 
can make a part of a revolution. The pitman, which is above the driving- 
axle, can be lengthened or shortened, so as to increase or diminish the 
stroke of the jaws, and the length of the toggles has been increased. It is 
probable that these changes will reduce the expense of stone-breaking by 
diminishing the breakage account, which, particularly with trap rock, is a 
serious item. 

Mr. J. L. Gillespie, C. E., gives me the following as the cost of break- 
ings 15,150 cubic yards of limestone during 1874-5-6-7, for the concrete 
used in the preservation of the Falls of St. Anthony. The machine, an 
8-inch by 16-inch, old pattern Blake, was run by water power, for which 
there was no charge. 

The cost and quantities were as follows, the stone being delivered at the 
breaker : 



18T4-5 3,452 cubic varda at, 

1875-6 8,284 

18T6-T 3.414 



.41. 
.81. f 
.18. 



cents. 



156 CONSTRUCTION AND MAINTENANCE OF ROADS. 

One cubic yard of stone produced about two cubic yards of broken 
stone, the void spaces in which amounted to 50 8-10 per cent. The break- 
ages were confined to some rubber springs, one back block, and two sets 
of jaws and cheeks. 

The cost of breaking trap on the Palisades is given as follows, the 
stone being sledged, to go into the jaws readily. 

Two crushers deliver 35 cubic yards of 2-inch stone per day, when 
working well ; 1 5 per cent of the time is lost by breakdowns. 

COST. 

1 engineman and fireman, at $2.50 $2.50 

2 laborers, feeding 1.25 2.50 

2 " screening 1.25 2.50 

*ij 50 

Coal, 1 ton 3.'50 

Oil and waste 1 .00 

Breakages. 5.00 

$17.00 

or, say, 57 cents per cubic yard. 

On Snake Island three crushers were arranged in a row, and the broken 
stone was carried by an endless belt to the revolving screen, whence it fell 
into the bins, so that no screeners were employed. The engine had one 
cylinder, 8 inches by 24 inches, and was running with 80 pounds of steam. 
The product was said to be 180 cubic yards per day when there was no 
breakdown. 

COST, 

1 engineman and fireman, at $2.50 $2.50 

3 laborers, feeding 1.25 3,75 

$6.25 

2i tons of coal, at $8.50 8.75 

Oil, etc 2.00 

Breakages 15.00 

$32.00 

Allowing for the 1 5 per cent, lost by breakdowns, the cost would be 
about 21 cents per cubic yard. 

At another place on the Hudson, two crushers, set face to face, 9-inch 
by 15-inch jaws, could deliver at the rate of 120 cubic yards per day, 
when no trouble occurred, but 100 cubic yards was a fair average. 

COST. 

Engineman and fireman ^ . . . . $2.50 

3 feeders 3.75 

2 screeners 2.50 

$8.75 

U tons coal, at $4. 6.00 

Oil,etc 2.26 

Repairs 10.00 

$27.00 

or 27 cents per cubic yard. 

Note. — A detailed statement of the cost, in time, of breaking stone is given in the Memoir on 
the Construction of a Masonry Dam. by J. J. E. Croes. Transactions o^ The American Society 
of CivU Engineers, No. GUI., VoL VIII., page 356 (February, 1875).— [Editor. I 



AD VERTISEMEXTS. 



157 




AVELING & P0R7^E:R 

STEEL STEAM BOAD-ROLIER. 



The Only Successful Steam Road-Roller ever Built. 



Messrs, Aveling 6^ Porter were Awarded the First Prize Gold 
Medal at the Paris Exposition, i88p. 



^^ BARNARD CASTLE ^^ 

Patent Street Sweeping Machines, 

Street Scrapers, etc. 



-6,000 BUILT. 



^W. C. OASTLER, 

Consulting Engineer on pighways, 

43 e;xchange: puac^, ne:w york city. 



158 



ARTICLES ON STREETS, HIGHWA YS AND 



INDEX TO READING ARTICLES 

ON 

Streets, Highways and Paving Materials, 

IN 

ENGINEERING NEWS. 

Note —This index refers only to reading articles of 
greater or less length on these various topics. Much 
further information as to prices paid in various localities 
will be found under the head of "News of the Week." 
Numerals refer to the page and Roman letters to volume. 



Asphalte: 

Val de Travers, 517, viii. 

An Ancient Pavement, 191, xiii. 

And its Application to Street Paving, by E. B. Ellice- 
Clark, Assoc. Mem. Inst. C. E., I5i, 202, vii. 

Antiquity of, 58, xi. 

Pavements, 129, xiii ; 39, 44, xix. 

New York Pavements, 169, xxii. 

For Paving, 291, xxii; 28, 136, 150, ix. 

Technical Uses for, 129, xviii . 

And Concrete Paving, 473, xxii. 

Effect of, on Workmen, 47, xiv. 

Deposits of California, 27, xvii. 

French Rock, 253, xiii. 

Kentucky, 99, xx. 

Italian, 242, xiv. 

Roadways of Berlin, Leon Malo, 329, 346, 94, xiii. 
Barber Asphalt Co. vs. James Brand, 119, xx. 
Beacon st., Boston, Improvement, 410, xix. 
Berlin Pavements, 261. xix. 
. Berlin and Paris Pavements, 57, xxii. 
Blast Furnace Slag for Paving Blocks, 118, xviu. 
Brick Street Pavements : 

Brick Street Pavements, 90. 296, 320, xvii; 330, xiv; 99, 
593, 596, 601, xxii. 

In Bloomington, 111., 552. x. 

In Toronto, Can., 17, xviii. 

In Berlin, 167, 31, 304, xii. 
Boston Street ImDrovement. West End. 292, xviii. 
Highways: 

Country, Apr. 28. 101, iv. 

Construction and Maintenance of Public, by E. B. 
EUice-Clark, C E., 378, 382, iii. 

Construction and Maintenance, 536, xix. 

in the United States, 9, xix. 

Highway Obstruction, Decision on, 454, xix. 
House and Street Drainage of Philadelphia, Condensed 
from a papei by R. Hering, read before the Engineers' 
Club of Philadelphia, 91, v. 
Pavements: 

Asphaltum, How Made, 76, xi. 

St. Louis Asphalt, 357, 572, x. 

Asphalt, 463, xx. 

New Orleans Asphalt. 491, x. 

Brick, 94, 275, 471, 554, 588, xxi. 
. Cedar Block, 282, xxii.: 494, xxi. 

Cedar in Toronto, 360, ix. 

Creosoted Wood, 427, xxi. 

Composite. 149, xi. 

Description of Granite Block, of Providence, R. I., Laid 
in 1880, 45, ix. 

Granite, 11, xii. 

Specifications for Laying Granite Block in Washing- 
ton, D. C, 334, V. 

Granite in London, 268, xviii 

The Grano-Metallic Stone, 234, xiv. 

The Guidet, 107, 132, ix. 

Impervious Street, 138, ix. 



PA VING MA TERIALS IN ENGINEERING NE WS. 1 59 

The Kerr, 30, xii. 

Movable, 479, xx. 

Berlin Wood, 34, xx. 

Buda-Pesth, 275, xxi. 

Here and Abroad, 186, xiv. 

In Detroit, 348, xxii. 

Houston, Tex., 49, 110, xxi. 

In Kansas City, Mo., 5i4, xix. 

In London, 295, v . 

New York City, 588, xxi. 

Pennsylvania Avenue, Washington, 323, xxi,; 272, v. 

The Pelletier, 51, ix. 

Suit in Pittsburgh, 357, xxi. 

In Philadelphia, 341, xix. ; 299, xxi. 

Cost of Wood in St. Louis, 102, xiii. 

Of American Cities, 322, xxii. 

In Washington, D. C, 323, xx. 

Relative Merits of, 475, xix. 

Macadam, St. Louis, Mo., 216, xxi. 

Macadam vs. Cedar Block, 416, vii. 

And Paving, 93, 592, xxi. 

Law, Pennsylvania, 395, xxi. 

Foreign Practice in, 317, xviii. 

Los Angeles Cement, 362, xxii. 

Effect of Heat on Cement, 17, xviii. 

Our City, 223, xviii. 

Cost of, in N. Y., xiv 

A New, 161. V. 

Street Pavements, Dec. 1, 337, iv. An exhaustive re- 
view of the sub.iect by Mr. Robt. Moore, C. E., St. 
Louis, before the University Club. Faults and ex- 
cellencies of the various systems, with estimates of 
the respective cost of each. May 6, etc., 146, 163, 170, 
179, iii. 

Abstract of an article by Gen. Q. A.Gilmore in the 
N. Y. Tribune, Feb. 19, 57, iii. 

Past, Present and Future, a paper by Jno. H. Sarerent, 
Read before the Cleveland Club of Engineers, xviii. 

An extract from a report of F. Shanly, City Engineer, 
Toronto, Ont., iii. 

In Chicago, 224, xviii. 

In St. Louis, by Thos. K. Mackland, before Soc of 
C. E., Feb. 18, '85, 355, xiii. 

For Heavy Traffic, 257, v. 

Of Pans. Translated for Inst. C. E., by D. K. Claik, 
Oct. 17, 334, V. 

In East Saginaw, Mich., 3, xviii. 

In Paris, Report by the Chief of Roads and Streets 
191, V. 

Of Washington, D. C, Annual Report on, 297, xviii. 

Of San Francisco, 321, ix. 

In Chicago, Cincinnati, Philadelphia and Baltimore, 
How Paid for, 132, xiii. 

Of Kansas City. W. B. Knight. Paper before C. E. 
Club, Nov. 29, 285, xii. 

Philadelphia, 168, 271, xiv. ; 217, xix. 

In Plainfield, N. J., 15, xvii. 
Paving: 

Brick for Street, xx. 

"Iron" Brick for, 395, xxi. 

A New Material for, 257, xiv. 

Road Metal and Setts in, 224, xx. 

Specifications, HoTiston, Tex., 396, xxi. 

Pitch Lake. Trinidad, 501, xxi. 
Report of Board of Experts on Street Paving, in Philadel- 
phia, xii. 
V Paving Blocks, Buda-Pesth, 494, xix. 
Paving Bricks, Bitumen, 203, xxi. 
Race Track Construction, by Chas. Holmes, E. Saginaw 

Mich., 242,259,266, vi. 
Roads: 

Cost of Bad, 102, xiii. 

Value of Good, 449, xxi. 

Common, 36, iii. 

Good County, 89, xiii. 



i6o ARTICLES ON STREETS, HIGHWA YS AND 

Our Country. 236, 269, xvii. 

Gravel, Senator Washburn on, 487, xix. 

And Road-Making, by W. B. Sears, Ch. Eng. F. & P. 
M. R. R., 85, xi. 

Making and Repairing, 314, xiv. 

Building, 381, xxi. 

Legislation for the American ^ tate, 203, 538, xxii. 

Specifications for Laying Macadam, 364, v. 

Macadam's Improvements in Making, 80, x. 

Width of, 186, xxil. 

The Construction and Maintenance of, by E. P. North, 
C. E., read before Am. Soc. C. E., April 16, 1879, 
228. 235, 243. 

Rollers, 251, vl. 

The Construction and Maintenance of Public, an 
English blue book, 223, Ix. 

Construction and Maintenance of French, 139, xxi. 

Construction and Repair of, 324, xxi. 

And iiridges in Georgia, 132, 101, xiii. 

Convict Labor in Georgia, 134, 444, xxi. 

Cost of Grading, in Minnesota, 271, xiv. 

Resolution of Illinois Highway Commrs., 327, xix. 

French, 160, 183, xxi. 

Illinois Laws relating to, 310, x. 

Making, in China, 6, xix. 

Law in Georgia, 329, xxi. 

In Illinois, 487, xix. 

In Illinois, Condition of, 145, xxii. 

In Long Island, Macadam, 529, xxii. 

In Massachusetts, 25, xxi. 

In Virginia, by D. H. King, 340, v. 

Improvements of, in Massachusetts, 317, xxi. 

New Jersey, 77, 512, xxii. 

Improvement of, in New York, 373, xix. 

In Pennsylvania, 25, 289, 305, xxi. 

Public, Their Construction and Repair: Seven Ques- 
tions by a Louisiana County Surveyor, 13, iii. 

Improvement of Prairie and Streets, by T. J. Nicholl, 
C. E., read before C. E. Club of N. W., Sept. 3, 1878, 
310, V. 

Making Prairie, 193, v. 

Private Roadways and Streets in England, 407, xiv. 

Michigan Ave., Chicago, Improvement of, 367, vii. 

Riverside Avenue, N. Y. City, Improvement of. Speci- 
fications, 326, 334, 342, iv. 
Road Roller, Aveling & Porter, 221, xxii. 
Road Making, The Science of, by Clemens Herschel, 
a First Prize Treatise awarded by the Mass. State 
Board of Agriculture, 148, 156, 164, 169, 176, 185, 194, 202, 
213, 221, 229, 235, iv. 
Road: 

Pike's Peak Wagon, 152, xx. 

Law in Roanoke, Va., 110, xxi. 

Bills, Penna.. 299, xxi. 

Specifications for Plank, 437, xxi. 

Shell, in Louisiana, 423, xix. 
Street Cleaning: 

Street Cleaning, 77, v 

Of Paris. Translation by L. Soulerin from the French 
of M. Vaissiere, Ch. Engr. Roads & Bridges, and 
read before C. E. Cluh of N. W., June 18, 215, v. 

In Paris, 238, viii; 94, xvii. 

Bill for N. Y. City, 246, 247, viii. 

And Maintenance, 75, xiv. 

In New York, 409, xiv. 

And Garbage Removal in N. Y., 394, xiii. 

English Street Cleaning Items, 280, xiii. ■ 

In Montreal, 57, vi. 

In Vienna, 285, xix. 
Street Sweeping; 

Street Sweeper, 179, 210, xviii. 

Street Sweeping, 476, xxi. 

In London, 151, iv. 

In Buffalo, 269, xviii. 

In St. Paul, 161, xiv. 



PA VI NG MA TERIALS IN ENGINEERING NEWS, 



Street: 

Excavations in Washington, D. C, 410. xxii. 

European House-Building and, 408, xix. 

Lights, Providence, R. I., 305, xvii. 

Refuse Disposal in London, 271 xvii. 

Sprinkling, Bournemouth, Eng., 285, xix. 

Sprinkling, 21, 436, 497, xxi. 

Naming, 249, 250, xix. 

Names, London, 506, xix. 

Naming in Mexico, New Method of, 44, xx. 

Renumbering City, 105, 115, viii. 

Maintenance in N. Y. City, 456, xviii. 

Maintenance in Paris, 13, xvii. 

Monuments, 4, xvii. 

Grade Intersections. 134. 150. xvii. 

Sign, 70, xvii. 

Commissioners, Boston, 308, xxi. 

Snow Removal in Paris, 17o, xvii. 

Act, Penna. Borough. 395, xxi. 

Crossings, Law of Over and Under Grade, 327, xix. 

Railway Accidents, 184, xix. 

Tramways, by Robinson Souttar, from Proceed- 
ings Institution Civil Engineers, 304, 312, iv; 322, 329 
339, 346, iv. 

Curb and Gutter, Philadelphia, 38, xvii. 

"Work, Decision on, 327, xix. 

Bill, Ives, 516, xxi. 
Street Refuse in Glasgow, Disposal of, 97, xii. 
Street Rails and Pavements, 80, xix. 
Streets: 

Resistance to Traction in, 106, ix. 

Length of London, 11, xii. 
Street Improvement, Elm St., N. Y , 134, xxi. 
Street Improvement, Laws for, in Cities, 71, iii. 
Streets, The Fee of, 366, ix. 
Streets, Olden Time, 24, xx. 
Street Paving, 256, 265, 350, vii. 
Street Paving, Special Assessments for, Court Decision 

Sustained, 101, xiii. 
Street Paving Specifications, 159, 227, ix. 
Specifications of Western Ave. Improvement, Albany, N. 

Y., Mar. 10, 63, iv. 
Sidewalk, Repairing of, in Washington, D. C, 309, ix. 
Subways and London Streets, 285, ix. 
Steam Rolling for the Maintenance of Roads in the 

Ardennes, Annales des Ponts et Chaussees, 447, ix. 
Sheet Asphalt Paving, 102, xifi. 
Slag Paving Blocks, 302, xiii. 

The Saddler Brick Pavement for Streets, Col. Flad's opin- 
ion of, 587, X. 
Tar Concrete Sidewalk, 539, xxii. 
Tar and Gravel Concrete Street Gutters, 130, iv. 
Telford Macadam, 221, xxii . 
Turnpikes in Lancaster Co., Pa., 256, xiii. 
Turnpiking and Underdraining Common Roads, by R. C. 

Carpenter. C. E., Lansing, Mich., 300, 306, iv. 
Wear of Horse Shoes on Macadam, 28, viii. 
Wood Pavement3 : 

Of Chicago, by E. A. Fox, C E„ a Paper read before 
the C. E. Club of N. W., Jan. 2, 1878, 14, 22, v. 

Of Chicago, 287, iv. 

In the Metropolis of London, by Geo. Henry Stayton, 
Proceedings Inst. C. E., 242, 253, 265, 277; 7, xii. 

In Berlin, 156, xi. 

In Paris, 462, 552, x 

In London, 531, 580, x. 

Wood as a Paving Material under Heavy Traffic. O. 
H. Howarth, Assoc. Inst. C. E. Proceedings Inst. 
C. E., 212, vi. 

Wood, Treatment of, for Street Pavements, by Thos. 
J. Caldwell and Thos. D. Miller, before St. Louis 
Club of Engineers, March 4. 1885. 322, xiii. 

Wood vs. Stone Pavements, 193, xii. 

Woud Pavement in Dalla,, Tex., Specifications for 
Bois D'Arc, 178. x. 



i62 AD VER TISEMENTS. 

RUDOLPH HERING, 

M. Am. Soc. C. E., M. Inst. C. E., M. Can. Soc. C. E., 

277 Pearl Street, New York, 
Civil and Sanitary Engineer. 

Designs for all work pertaining to Sewerage 
and Water Supply of Towns. 

SPECIAL ATTENTION GIVEN TO ROADS AND PAVEMENTS. 

F. A. DUNHAM, 

Civil Engineer. 

Engineer of Union County (N. J.) Road System, 
No. 7 Park Avenue, Plainfield, N. J. 

SPECIAL ATTENTION GIVEN TO THE PAVING AND IM- 
PROVEMENT OF STREETS AND ROADS. 

Plans, estimates and specifications for engineering 
wort-s furnished and construction superintended. 

MASONRY CONSTRUCTION. 

By IRA 0. BAKER, C. E. 

Materials— Methods of Using Materials— Foundations- 
Masonry Structures— Etc., Etc. 
Illustrated with numerous cuts and six folding plates. 
8vo. Cloth, $S'00. 
for sale by 
THE ENGINEERING NEWS PUBLISHING COMPANY, 

Tribune Building, New York. 

ROAD LEGISLATION FOR THE 
AMERICAN STATE, 

• By J. W. JENKS, Ph.D., Knox College, Galesburg, III. 



7 5 C K JSr T S . 



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